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mDrT'i'r^TSEF- • 192. 



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CONCDETE 

" . AMD 

CQNSTBUCri QNAL EN GINEERING 

THE OFFICIflliLY flPPOlHTED JOUHNAIi OF THE CONCRETE INSTITUTE 

VOL. XVI. 1921. Nos. 1 to 12. 

A MONTHLY JOURNAL for Engineers, Architects, 
Surveyors & Contractors and all interested in Cement, 
Concrete, Reinforced Concrete, Fire=resisting Construction 
and Structural Steel, 



VOLUME XVI. 



.<,•' 






.-Jll Rights Rrserved 



Published at 4 Catherine Street, Aldwych, London, W.C.2. 
Editorial Offices at: 35 Great St. Helens, E.C.t,. 

1921 



CONCRETE 

AND 

CONSTEUCriONAL ENGtNEEKING 



Ik 



I 



Volume XVI. 1921. 

Published at 4 Catherine Street, Aldwych, London, W.C.2. 

Editorial Offices at : 35 Great St. Helens, E.C3. 






INDEX 



b60KS, new : 

Artificial Road Material 

Calculations for Reinforced Concrete without the 

Use of Formulae . . 
Columns. By E. H. Salmon 
Concrete Designers' Manual. G. A. Hool and 

C. S. Whitney 

Concrete for House, Farm and Estate. Bv Fred 

Ballard 

Engineering and Building Foundations. By 

Chas. Evan Fowler 
Engineering Construction. W. H. Warren 
Handbook of Building Construction. By Geo. .■\. 

Hool and Nathan C. Johnson 
Housing Experiments at Hatton, Warwickshire. 

Some 
Making Moulds of Plaster. By A. Moye . . 
Masonry Structures. By Fred. P. Spalding 
Old London lUustrated. By H. A. Cox . . 
Popular Handbook for Cement Users. By Lewis 
Chandler . . . . . . . . . . 53 

Practical Geometry for Builders and .Architects. 

By J. E. Poynter . . 
Reiriforced Concrete Construction. M. T. Cantell 
Reinforced Concrete Design. Vol. II. By Oscar 

Faber, O.B.E., D.Sc, etc. 

Reminiscences of a Municipal Engineer. By H. 

Percy Boulnois, M.Inst. C.E. 
Report of the Third Congress on Housing, The . . 
Structural Engineers' Pocket Book. The. By 

Ewart S. Andrews 
Technical Dictionary, A 
Tonindustrie Kalender, 192 1 

Useful Engineers' Constants for the Slide Rule. 
By J. A. Burns 
CEMENT NOTES : 
Balling of Cement, The 
Calcium-.\luminate Cements 
Cement Grout 

Cement Testing by Independent Experts . . 
Colour of Portland Cement . . 
Concrete Aggregates . . 
Concrete Improvers . . 
Concrete Mixing 
Doubtful Aggregates . . 
Education of the Conrretor, The . . 
Expansion and Contraction of Concrete . . 
Hydrated Lime 

" killing " of Portland Cement, The 
Labour Economy in Cement Handling 
Loam and Clay in Concrete Aggregates . . 
Nominal and True Fineness of Cement 
Portland Cement of the Future 
Portland Cement v. Lime 
Progress in Cement Manufacture . . 
Rough and Ready Tests for Cement 
Slag for Concrete 
Storage of Cement . . 
Substitutes for Cement 

Thermal Effects on Heating Cement Meal. . 
Value of the Brand in the Portland Cement Industry 

CONCRETE MACHINERY : 

Care of Concrete Mixers, The 

Desch Mi.xer, The 

Kirk Mixer, The 

Martin Harvey Block-making Machines, Tne 

Tonkin Mixer, The . . 

CONSTRUCTIONAL WORK : 

Acid Tower for The Riordon Company, Ltd 

Hawkesbury 
.\nglo-South American Bank, Valparaiso . . 
.\rdenho Bridge, The. . 
Ascot Grand Stand. By Claude Pain 



467 



468 
827 

746 



19S 

735 
40.'i 
404 
828 



686 
745 



133 

820 



467 
1 90 



478 
2fi9 
406 
740 
406 
614 
269 
824 
13^ 
740 
S23 
824 
197 



. . 478 
61 
. . 198 
.. 613 
. . 270 
. . 681 
13'. 343 
. . 54'^ 

131 



611 
402 
144 
473 



193 
364 

.S2^ 
56.5 



32- 



PAGE 

643 
365 



Birkenhead. Alwen Water .Supply 
Bridge, New Arterial Road, Hastings 
Chile Telephone Co., Ltd. . . 
Circular Coal Storage Bunker at Chapeltown 

R. Stubbs 

Colchester (ias Company, Reinforced Concret 

Work at The 
Concreting Wooden Piles, New Method of 
Craig, Taylor & Co., Ltd., Stockton-on-Tees, Wharf 

for Messrs. . . 
Extensions to the Port of Nantes and the Loire 
Fish Freezing Plant on the Island of St. Pierre 
Flax Rettery in Belgium 
Fordson Factory, The. By H. C. Johnson. . 
Gateshead Refuse Staith 
Gosgen Water Power Station 
Grain Store at Battersea 
Gravel Hopper, A 700-Ton. By V. Elmont 
Hangars, Reinforced Concrete 
Hide and Leather Realty Co. Building 
Hollow Concrete Piling 
Leamington Circular Reservoirs 
Leeds General Infirmary 
London and North-Western Railway, Concrete 

Construction on The 
Macquarie Bridge 
Par River Bridge 
Petrol Depot at Wandsworth 
Piling, Some Notes on 
Printing Works, Prague 
Railway Reconstruction Work in Belgium 
Railway Wagons, Concrete . . 
Repairing a Concrete Vessel. By V. Elmont, B.Sc 
Silo, Prague 

Smcthwick, Machine Shop at 
Southport Housing Scheme . . 
Suspended Drain. By W. L. Scott 
West Bank Dock Electric Generating Station 
Wireless Tower 672 ft. high in Japan 

Notes on Constructional Work : 
Agricultural Silos 
,\rch Design Construction . . 
Ballantyne Pier, Vancouver 
Bevan Cement Works, New Offices for . . 
Bridge, Dubissa River, near Lidoviani 
Bridges with Floors below Water Level . . 
Bridges in Tchecho-Slovakia 
Bristol University 

Coal Store at Heidelberg Gas Works 
Concreting River Banks 
Failure of a Concrete Pile Bridge due to Slippin 

Foundations 
French Tidal Power Scheme 
Garage at Grenoble. Large French 
(larden Frames, Concrete 
Grain Elevator, N.S.W., A Large . . 
Hasslacher Weir Dam Wall . . 
Hastings Ladies' Baths 
Highway Bridge in Sierra Leone, Concrete 
Hospital Construction, Concrete in. . 
Hydro-Electric Power Station in Lower .-Austria 

National 
Irrigation in the Rio Negro Valley. . 
Kiln Construction, Concrete in 
La Louviere, Bridge at 
Long-Span Concrete Roof Arches for Chicago 

Garage 
Moulding Concrete under Water, A New Method of 
New Application of Concrete for Internal Decorative 

Partition Walling 825, 826 

Pressure Conduit of Reinforced Concrete, A . . 820 
Portuguese Water Tank, A . . ■ ■ ■ ■ 820 

Queensland's New State Cold Stores . . . . 207 

Race Track for Paris, A . . . . ■ ■ ■ ■ 620 



147 

79 
380 

46 

705 

53» 

51 

5,491 
215 
453 
769 
149 
318 

21, 34 
378 
321 
421 

699 
2,265 
448 
769 
378 
521 
390 
263 
597 
522 
295 
425 
499 
776 
459 



571 
757 
620 
646 
399 
689 
469 
549 
310 

685 
832 
644 
549 
552 
o, 347 
441 
832 
541 

732 
616 
744 
618 

741 
576 



Railway Trucks .. ,,:• , 

Reconstructing a Railway Viaduct 
Regent's Canal Bridge . • ■ • ' , r,\^ 

Repairing Stone Arch Aqueduct with Cement Gun 
Safes, Concrete . . „ •. ■ • • ' ' ,„ 

Sewer Ventilating Tubes, Reinforced Concrete . . 

Silos at Zschadrass 

Siphons, Concrete 

Sul Espirito Santo Viaduct . . 

Tunnel Lining with Concrete •• jcik" 

Use of Steel Forms for Concrete Columns and Slabs 
Water Engineering, Concrete and . . 

Water-tight Joint for Tank Walls 

Wharf at Costa Rica 

EDITORIALS : 

Action of Sea Water and Oil on Concrete, The 

American Methods . . ■ •. 

Beauty and Economical Building 

British Empire Exhibition . . 

Building Trades Exhibition, I he .. •■ i4d 

Cement Prices 

Cement Supplies •• •■ .'• ci'„^ 

Collapse of the Government Housing Scheme . . 

Commercial Motor Show, The 

Concrete and Architecture 

Concrete Industry, The . . • • ■ • ■ ; 

Concrete Institute, A step forward on the part of the 

Concrete Institute and the Industry 

Concrete Institute and Research, The 

Concrete Tanks for Fuel Oil Storage 

Cost of Concrete Cottages, The 

Cost of House Building, I he Vu ' ' 

Decorative Treatment of Concrete, i he . . • ■ 

Department for Scientific and Industrial Research. 

The ^ 

Experimental Roads in Somerset 

Failure of a Concrete Floor 

Fire Resistance of Concrete . . • ■ ' ' , . . ' 

Ministry of Health, Standardisation and New 

]\Iethbds of Construction Committee ; Report ot 

the First Year's Work .. •• ;;. , ' ' 

Official Investigation into the State Highwav 

System of California 
Output in Building Work . . • • • • 

Plea to Architects for Courage in Designing 

Problem of Collaboration, The 

Progress of Concrete Construction in 1920 

Slab Concrete Roads 

Surface Decoration of Concrete, The .. •■ 

Two Recent Failures of Reinforced Concrete Work 

in America ,\,, , • -n 

Use of Clinker for Blocks and Slabs, I he . . 
Vision of the Future, A 

GENERAL : 



PAGE 

547 

151 
273 

548 

533 

616 
688 
151 
431 
757 
233 
759 



419 

2H 
632 



3 

4 
489 
696 
145 
75 
285 
3 
417 
632 
418 
560 
559 



695 

78 

'^31 



487 
561 
351 
766 
I 
14b 
765 

007 
286 
696 



HOUSE AND COTTAGE BUILDING 

America, Concrete Houses in 
American Domestic Architecture . . 

Amesbury, Houses at 

Cheam, A Concrete House at 
Chepstow Housing . . • • • • • 

Folkestone, Some Concrete Houses built at 
Hatton, Houses at . . 

Hayes Housing Scheme 

Liverpool Housing Scheme 

Lowestoft Housing Scheme . . .. • 

Marton Grove, Garden Suburb, Middlesbrc 

Norwich Housing Scheme 

Petersham, House at 

Southport, House at . . 

Treatment of Small Concrete Houses 

Walsall, Houses at 

Weaverham Housing Scheme 

Welwvn Garden City 

White'leaf, House at 

Worcester, Cottages at 

HOUSING NOTES : 

Apartment Houses m \^ ashmgton . . 

Australia . ■ 

Crossens, Concrete Houses 

Dublin, Experimental Houses at . . 
Houses Ready Made . . ; • ^ ' ' 

Housing Problem and Local By-Laws . 
HousingSchemes 71, 138, 207,279, 349, 4ii, 481, 555, b- 
Italy and France, Concrete Houses m .. ' ' °^ 

Londonderrv, Proposed Housing Scheme . . ■ • 059 

Ministry of Health and Housing .. •■ - /^ 

New Methods and Materials . . 73, 141, 2°/, -79, 405 



American Concrete Institute, The . . ■ - 394, 

American Flat Slab Type of Building, 1 he. By 

A. E. Wvnn . - • ■ A' ^ V^ r- ^^' 

Arched Bridges of Wide Spans. By Dr. F. Em- 
perger • • • • ■ • ' •" c-i.' ' 

Bath and West and Southern Counties Show . . 
Building Trades Exhibition . . • ■ 205, 281. 

Concrete Institute, The 35, 103, I59. 243, 297, 

432, 509, 577, (>(>5, 719; 
Concrete Roads and their Construction . . . • 

Correspondence . . • - 480, 550, 683, 748 

Cribs and (iranaries . . • • • • • • • • 

Decorative Treatment of Reinforced Concrete. Jly 

Godfrey Page 584 

Derby Royal Agricultural Show 

Don'ts for Concrete • •■ 794 

Excavating and Conveying Plant, Saiiennan Ex- 
cavator . . • • ■ • ■ • • • 
Fire Resistance of Reinforced Concrete \A^ork 
Floor Types— Reinforced Concrete. By W. H. 

Thorpe 
(Irain Dust Explosion 

Ickes Railway Tie, The 

Italy, Reinforced Concrete in 

New Method of Concrete Mixing. A 

Obituary, Francois Hennebique .. ,•• ^ • 

Organisation of a Contracting Firm. By Oscar 

Faber . . • • ■ • • • ■ • 

Public Works and Roads Exhibition, Ihe 
Questions and Answers Relating to Concrete 67, 
272, 347, 407, 4<'9, 542. 550, hi2, 
Recent British Patents Kelatiiig to Concrete 255, 
Reinforcing Steel Cutting and Bending Lists. By 
H. P. .\tkinson 

Royal Agricultural Show • • 

Simple ICxainples of Reinforced Concrete Design. 

By Ocsar Faber 71°. 

Spain, Reinforced Concrete in 

Stoneiienge 

Study for a Warehouse 

Successful Repair of a Concrete Ship Bottom, Ihe. 

By Walter R. Harper 

Use and Abuse of a Concrete Stage, The . . 
Use of Concrete on Farm and Estate, The. By 
Capt. W. J. Pulford 



442 
178 



804 
464 
329 
368, 
790 
748 
826 
604 

,674 

514 

,829 

608 
748 

575 
537 
737 
450 
402 
268 

Mv) 
813 
:3f'. 
747 
524 

.302 
514 

77« 
250 
287 
795 

811 
■95 

655 



. . 155 
731, 782 
.. 237 
. . 353 
. . 240 
. . 309 
■ • 735 
105 
22 
.. 502 
.. 587 
303, 533 
. . 152 

• ■ 425 
30, 112 

.. 152 

• • 733 
.. 118 
. • 234 
. . 506 



469 
589 
659 
757 
589 



Paisley, Houses at 

Poole . . 

Port Talbot 

.South Shields . . 

Stirlingshire . . 
INDUSTRIAL NOTES : 

Roofing Tiles . . 
MEMORANDA : (General) 

Aberdeen . . • • . ,•.■.■ Vi,., 

^ir Ministry and the Gnssell Prize, The . . 

.Auckland Main Drainage Scheme . . 

Australia, Pipes in . . ■ • • ■ 

Belt Conveyors for placing Concrete 

Birmingham Architectural Association . . 

Bridge over the Muko River 

Brine Troughs, Concrete • ■ „ • • 

British Standard Channels and Beams 

Cement for the .\rgentine . . 

Cement Linings of Water Flumes . . 

Chimneys, Concrete . . 

Cinerary Monument, A 

Circular Concrete Structures 

Coaster Launched at Preston • • , ; ;, ,. 1 '. 

Coke Breeze, A Storehouse at East Ashland, Ken 
tucky 



756 
.. 693 
. . 481 
. . 469 
481, 693 



409 

fxj 

759 
721 
620 
768 
117 
693 
151 
745 
756 
203 
205 
476 
659 
205 

704 



ColnSniesRegistered:kew7^,209;282.4i5.486.763,838 



Concrete Block Buildings in India 

Concrete Tanks for Carbolic -Acid . . 

Concrete Utilities Bureau . . • ■ p„„;,;„rotive 

Cost of Laying Block and Brick and Comparatixe 

Strength . . • ' , ' " 

Crayford Improvement Flans 
Curb Bridges, Concrete 
Curiosities near Salisbury 
Doncaster— New \\ater Tower 
Dublin Uni\ersity . . • ■ • • 

Effect of Paint on Reinforcement . . 

Effect of Rain on Houses, The . • 
Enquiry into the High Cost of Buildmg . . 

l-:xpansioii Joints in Buildings 

1-inish to Concrete Floors, A 

I'ish Troughs, Concrete • • • • • ■ ' " 

Floor Test, A . . 

I-Omulations for Sewers 

(,.is I'.uginc Flxhaust Silencer 

Ccrniau Concrete .Association 

(.unilri River, Bridge over the .. ■■ •• 

('.utters. Concrete .-• 

Headgear Frames, Concrete • • • • ' " 

Holes in Concrete 

lini'iovcinents in Concrete Ships .. 

Intrnsling Job at Brussels, An 

lomling Concrete Structures 

Keeping Concrete Chutes Clear ■ ' 

Lagos Hartxjur 

Lamp Posts at Croydon 

Leeds .Agricultural Show 

I.vonshall War Memorial 

Mattress Blocks, Concrete ■ ; • 

Metal Forms and Economy m 1 amt 

Motor Ships, Concrete 

New Bridges for Norway ■ • 

New Method of Making Concrete, .\ • • 

New .Methods of Proportioning Concrete . . 

New Kevemie Oflices, Karachi 

New Zealand War Memorial, A • • 

Nova Scotia, A Concrete Motor Vessel m . . 



553 
768 

756 

137 
743 

71 
276 
721 

71 
137 
S20 
III 

94 
128 
664 
128 
553 
20 s 
408 
614 
821 
732 
475 
689 
477 
449 
<«>3 
424 
276 

(>20 

603 
186 
343 
759 
756 
742 
3«7 
553 
739 
128 



PAGE 

Novel Method of Concrete Roof Construction . . (164 
Oil for Concrete Moulds and Shuttering . . . . 742 

Patent Applications, Recent 74, 210, 416, 486,627, 764,838 
Permanent International Association of Road Con- 



gresses 
Personal 

Pillars with a Stone Core, Concrete 
Pipes in India, Concrete 
Pipes at Manchester, Concrete 
Placing Concrete in Cold Weather . . 
Pont de la Tournelle, Paris . . 
Pozzolano and its use in Concrete . . 
Proportioning Concrete, New Methods of 
Prospective New Concrete Work 139, 



• • 555 
73,612 



609 
.. 138 
.. 69 

• ■ 742 

• • 317 
279- 349. 

413, 483, 557, 623, 693, 762, 837 
Proposed Portland Cement Works, Jamaica . . 833 
Protection for Reinforced Concrete against Elec- 
trolysis 
Pumice Stone and Salt 
Railway Slefpers, and Transmission Poles . . 
Railway Wagons 
Reconstruction in Belgium . . 
Reinforced Concrete Design 
Reinforced Concrete versus other Materials 
Removal of Forms in Concrete Work 
Repairing Concrete Floors . . 
Repairing Leaks in Concrete Water Tanks with 

Brass 
Rust Prevention in Reinforced Concrete . . 
Sash Weights of Concrete 
Scientific and Industrial Research . . 
Seven Subjects we should know more about 
Shipbuilding . . 
Signal Posts, Concrete 
Signal Posts on S.E. Rly., Concrete 
Silos, Concrete 
Sinks, Concrete 
Some Things to be learned about Concrete . . ?43 

South Wales Institute of Engineers . . . . 128 

Spey Bridge . . . . . . . . . . . . 469 

Standardisation of Blocks . . . . . . . . 476 

Supply of Building Materials . . . . . . 622 

Tanks for Oil Storage, Concrete .. .. .. 721 

Tenders 73, 143, 209, 281, 350, 413, 483, 558, 625, 

694, 762, 835 
Trade Notes, Catalogues, etc. 74. 144, 209, 486, 555, 

622, 761, 833 
Vancouver Port Development . . . . . . 69 

Water Gauge for Concrete . . . . . . . . 190 

Water Tanks 718 

Watertight Concrete, How to Obtain . . . . 29 

Window Frames, Concrete . . . . . . . . 822 

Wood as Reinforcement . . . . . . . . 743 



401 

452 
646 
263 
242 

128 

431 

69 

69 

^73 

820 

73 

207 

5-2 



410, 411 
■ ■ 732 
• • 424 
.. 822 



NEW METHODS OF CONSTRUCTION 

Anchor Tie System, The 

Calver System., The . . 

C.D.L. System of Concrete Construction . . 

Elzed System, The . . 

Evans and Howarth Cavity Wall . . 

Express Concrete Building Form, The 

Factory-made Concrete Blocks 

Hessian Fabric 

Houston Method of Cottage Construction. . 

McLeod's Unit System 

New Methods relating to Concrete Construction . . 

Simple Contrivance for holding down Rails to 

Concrete Foundations 
Spade Shuttering 



•• 344 
610 
.. 118 
544. 551 
.. 274 
. . 830 

• ■ 755 
.. 62 

• • 677 
470 
3" 



134 
64 



RECENT VIEWS ON CONCRETE AND 
REINFORCED CONCRETE : PAPERS 
READ : 

Applic.Ttion of Cementation to Mining. H. Stan- 
dish Ball 

Cement Gun, The 

Chimney Construction 

Civil Engineering Conference 

Contractors' Plant in Reinforced Concrete Con- 
struction 

Floor Finish Concrete 

Fran<;ois Cementation Process 

Geology of Constructional Stone. By J. Allen Howe 

Harbours and Docks, Reinforced Concrete 

Land Subsidence and its Effect on Concrete and 
Other Structures .. .. .. .. 511,579 

Metal I'onns, Application to Reinforced Concrete 
Construction . . . . . . . . . . 397 

Modulus of Elasticity of Concrete. By Prof. F. C. 



382 
533 
398 
590 

394 
399 
591 

244 
591 



Lea 

Oil Storage Tanks, Concrete 

Railways, Reinforced Concrete on . . 

Reinforced Concrete for Ship Construction. 
T. B. Abell 

Safeguards against Fire Hazards . . 

Some Methods of Securing Impemieability in 
Concrete. By E. S. Andrews 

Special Application of Reinforced Concrete in 
Docks. By H. J. Deane 

Stresses in Stcelworl;. J?y S. Bylander . . 

Tests on High-Tension Steels in Reinforced Con- 
crete Design. By H. Kempton Dyson . . 

Wharves and Breakwaters, Reinforced Concrete for 



435, 646 
■• 398 
.. 590 

By 

127 
.. 398 
in 

3<''9 



39 

298 



161 
592 



PAGE 

RESEARCH : 

Abrasion Test for Concrete . . . . . . . . 718 

Fire Resistance of Concrete and Reinforced Con- 
crete . . . . . . . . . . 660, 722, 799 

How the Quantity of Mixing Water Affects the 

Strength of Concrete. By Duff A. Abrams . . 663 
Modulus of Elasticity of Concrete. By Prof. F. C. 
Lea . . . . . . . . . . . . 435, 646 

New Design Data for Cement Slabs . . . . 687 

Portland Cement, Its Testing and Specification, 
British and Foreign Methods. By R. E. Strad- 
ling . . . . . . . . . . . . 169, 223 

Proportioning Tests made at Washington Univer- 
sity 730 

Service Tests on Concrete Floor Treatments . . 187 
Tanks for Westinghouse Electric and Manufactur- 
ing Co., U.S..\., Tests of . . . . . . . . 50 

Tests on High-Tension Steels in Reinforced Con- 
crete Design. By H. Kempton Dyson . . 161 
Wharves and Breakwaters, Reinforced Concrete for 592 
Notes on Research : 

Clinker Concrete .. .. .. .. ..411 

Comparison of the Slump Test and the Flow Table, 

A 535 

Data for Cement Slabs, New Design . . . . 687 

Effect of Colourings on Concrete Strength deter- 
mined by Test . . . . . . . . . . 552 

Effects of Crusher Screenings in Concrete. . . . 609 

Effect of Water on the Strength of Concrete. By 
Duff. A. Abrams . . . . . . . . . . 594 

Research . . . . . . . . . . . . 424 

Rodding Concrete, The Effect of . . . . . . 534 

Secondary Stresses in Monolithic Structures and 
How to Calculate Them. By R. J. Harrington 
Hudson . . . . . . . . . . 715, 784 

Setting Tests on Concrete . . . . . . . . 535 

Silt in Concrete . . . . . . . . . . 411 

Vibration in Moulding Concrete, Effect of . . . . 535 

Wear Tests of Concrete . . . . . . • • 534 

ROADS : 

Experimental Roads in Somerset . . . . . . 695 

Fracture of a Reinforced Concrete Road owing to 

E.xpansion . . . . . . . . . . . . 536 

North Circular Road, Willesden (Section No. i) 572, 684 

Reinforced Concrete Roads. By D. Edwards . . 445 

Simple Rules for Concrete Road Construction . . 48 
Some Impressions of Concrete on the Western 

Continent. By A. Dryland, M.I.C.E 728 

Wilmington Hull, A Concrete Road at . . . . 342 

Works and Factories, Roads for . . . . . . 124 

Notes on Roads : 

America . . . . . . . : . . . . 614 

Australia . . . . . . . . . . . . 469 

Automatic Records of Concreting Operations . . 767 

Bath's Concrete Roads . . . . . . . . 202 

California, Reinforcement of Concrete Roads in . . 203 

Canada, Concrete Roads in . . . . .. . . 393 

Canada, Concrete Road Development in . . . . 458 

Cement and Iron Roads . . . . . . . . 411 

Clean Concrete Paving Joints with Automobile 

Exhaust . . . . . . . . . . . . 833 

Concrete Roads in America . . . . . . . . 614 

Cost of Concrete Roads . . . . . . . . 460 

Cross Road Signs, Concrete . . . . . . . . 137 

France, Roads in . . . . . . . . . . 619 

Joints in Concrete Roads . . . . . . . . 249 

Lyons, Road at - . . . . . . . . . . 411 

Middlesbrough . . . . . . . . . . 262 

New Stretch of Concrete Highway in British 

Columbia . . . . . . . . . . . . 126 

Our Roadways . . . . . . . . . . 693 

Providing for Expansion in Concrete Roads . . 768 
Road Constructional Requirements from the 

Users' Point of View . . . . . . . . 202 

Road Making 395 

Seaham Harbour Concrete Road . . . . . . 26Z 

Southsea . . . . . . . . . • . . 460 

Spraying Concrete Road Surfaces to Pre\ent Rapid 

Drying 615 

Wheelways, Reinforced Concrete . . . . . . 395 

THEORETICAL : 

Calculations for Continuous Beams with Third- 
Point Loading . . . . . . . . . . 647 

Concrete in Theory and Practice : Reinforced Con- 
crete Simply Explained. By Oscar Faber, 
O.B.E., etc. .. 57,129,191,266,327,400,461 

General Theory of Moving Loads, The. By V. A. 

Bailey . . . . . . . . . . • • 360 

Modulus of Elasticity of Concrete, The . . . . 646' 

Notes on Fyson's Shearing Resistances of Reinforced 

Concrete Beams. Comments by Oscar Faber . . 92- 

Reinforced Concrete Columns . . . ■ ■ ■ 442^ 
Reinforced Concrete Simply Explained. By Oscar 

Faber, O.B.E. . . 57, 129, 191, 266, 327, 400, 461 
Secondary Stresses in Monolithic Structures and 
How to Calculate Them. By R. J. Harrington 

Hudson 715, 784 

Shearing Stresses in Rectangular Reinforced Con- 
crete Beams. By Alfred Fyson, M.I.C.E. 14, 85, i 90 
Simple Examples of Reinforced Concrete Design. 
By Oscar Faber 710. 77& 




Volume XVI. No. i. London, January, 1921. 

EDITORIAL NOTES. 



THE PROGRESS OF CONCRETE CONSTRUCTION IN 1920. 

HOUSING. 

There is at this stage of the Government housing programme ample evidence 
that the prejudice which at one time existed in the minds of the public against 
concrete houses is fast disappearing. While those who had had experience 
of concrete, never doubted its constructional value and economy as a 
material for building small houses, the Englishman's love of the national 
building material — bricks and mortar — had to be reckoned with, and old preju- 
dices die hard. However, a combination of post-war circumstances — the shortage 
of bricks, the scarcity of men skilled in old methods of building and the high 
wages demanded by them, in conjunction with the shortage of houses — has given 
newer methods an opportunity to prove their value, with eminently satisfactory 
results. The railway congestion which followed immediately on the cessation 
of hostilities seriously hindered the transportation of bricks, and called atten- 
tion to the fact that concrete could invariably be made from materials found 
on, or near to, the site, thus eliminating altogether the need for transporting the 
greater part of the materials. 

All these factors are reflected in the returns of the IMinistry of Health, which 
show that up to the end of 1920 contracts had been definitely placed for about 
20,000 houses by special methods of construction, 5,000 of which were actually 
under construction, while contracts for nearly 18,000 more were under considera- 
tion. In addition, some 3,500 concrete houses were being erected by private 
persons with the aid of the Government subsidy. 

So far the shortage and uncertainty of delivery of cement supplies have some- 
what handicapped concrete construction, but we are assured that every effort 
is being made to secure a larger production, and that an increase on the pre- 
war output is confidently anticipated by the manufacturers in the near future. 

A multitude of different systems of building small houses in concrete have 
been evolved and developed since the war, and approved by the Ministry of 
Health, mostly consisting of various types of shuttering for monolithic wall con- 
struction, solid blocks for forming cavity walls, and hollow blocks of various shapes. 
Many of these systems have been described in this journal, and we woukl emphasise 
the fact that the schemes dealt with each month during the past year are all actu- 
ally being, or liavc been, carried out, some of them comprising hundreds of houses. 

When it is considered that. exce})t for a few experiments, concrete houses 
were almost unknown in this country before the war, the number at present 
under construction and under consideration can on]\- be descrilied as phenomenal. 



THE PROGRESS OF CONCRETE CONSTRUCTIOJW 

When the very small sum needed for the maintenance of concrete houses is fully 
realised, we predict an even greater vogue and popularity for them. 

CONCRETE ROADS. 

Another application of the material, and one which promises a wide 
development in the future is that of concrete roads. This form of construction is 
steadily increasing in favour and has been adopted in several places during the year, 
among the most recent being those at Bath, Newbury, South wark (where something 
like twenty-five streets have been paved with concrete) and in Northumberland- 

LABOUR-SAVING DEVICES AND MACHINERY. 

Another feature of the past year has been the improvement in labour-saving 
devices, especially block-making machines for both hand and power. Handy, 
efficient, and serviceable machines can now be obtained to suit either the con- 
tractor who requires a battery for a big scheme or the small builder who is putting 
up a couple of houses. We were told the other day by one such small builder that 
a hand machine he bought as an experiment for use in the erection of three houses 
had paid for itself on that job alone by the saving in labour— and he still had the 
machine in good condition. There is, we believe, a great scope for the more 
extended use of machinery on even small jobs, both in reducing the cost and 
expediting the work. For instance, small hand mixers (which can be adapted 
for power) can now be obtained for about ;^5o, and not only is the capital outlay 
soon recouped by the saving in labour but better concrete is obtained than can 
possibly be the case when the mixing is done with a shovel. Elevators and gravity 
conveyors are also being more extensively used, and are proving their worth. 

OTHER DEVELOPMENTS. 

Although the past year has been chiefly notable for the development of 
concrete in the direction of housing, many large public buildings, factories, and 
warehouses have been erected in this material, and a notable event was the 
completion of the first large concrete office building in the City of London, namely, 
the eleven-storey Commercial Bank, in Gracechurch Street, from the designs of 
Mr. Gould Wills, A.R.LB.A. The restrictions on so-called "luxury" buildings 
and high costs have affected the total number of large buildings erected, but 
concrete construction has not been so badly hit as other forms ; in fact, in 
many cases local authorities have stipulated that new buildings shall be erected 
m concrete, in order to conserve labour which could be employed on housing. 

If only a satisfactory agreement could be brought about with labour, so 
that a certain amount of stability could be attained and definite tenders sub- 
mitted without vague provisions as to increases owing to unknown advances in 
wages and materials, the industry would go ahead at an even greater rate than 
at present, with advantage to the very large number engaged in the concrete 
and allied industries and the country at large. 

THE MINOR USES OF CONCRETE. 

Durmg the past year, also, there has been a great expansion in the applica- 
tion of concrete to minor uses, such as fence posts, pipes, troughs, tanks, silos,, 
poultry houses and pigstyes, and many firms realising the increasing demand 
have taken up the manufacture of such products. In spite of this, however, 
there is still room for contractors and others, who will take up this work and put 
upon the market such articles as people would rather buy than make for themselves. 



2 



I&iSomSN'S''^ THE CONCRETE INSTITUTE AND THE INDUSTRY. 



The Railway Companies, too, have made continual progress, and during the 
past twelve months have considerably widened the scope of their concrete work. 
The London & South Western Railway Company, for example, have been so 
satisfied with a certain number of experimental telegraph poles which they have 
had in use for some time that they propose to adopt them very extensively on 
their system. 

CEMENT PRICES. 

A LONG and exhaustive report has recently been issued on Cement and Mortar 
by a Sectional Committee appointed by the Standing Committee on the Investi- 
gation of Prices and Trusts. It is satisfactory to note that while the financial 
position of the cement industry has substantially improved owing, in some measure, 
to its profitable export trade, no unreasonable increase in the home trade price 
has occurred, and that the trade therefore is acquitted of any suspicion of profit- 
eering. It is pointed out that in the period and in the cases under review the 
percentage increases in the total costs of production are substantially more than 
the percentage increases in the average home trade selling prices. A reduction 
in cement prices isnot anticipated unless the difficulties of fuel, labour and machin- 
ery replacements are overcome. Amongst other recommendations it is suggested 
that the existing voluntary limitation of exports should be continued so long as 
the urgent home trade demands are unsatisfied, and it is further suggested that 
the authorities should aid the trade by ensuring the necessary supplies of suitable 
fuel and providing the necessary transport facilities. 

THE CONCRETE INSTITUTE AND THE INDUSTRY. 

Mr. Fiander Etchells' admirable Presidential Address to the Concrete Institute 
(reported in our last issue) might very well be summed up as a plea for good con- 
crete and sound construction, by improvements in the three cardinal requirements 
necessary to attain that end — research, education and workmanship. 

We have in these pages frequently urged that the work of the Industrial 
Research Board should be considerably extended, and we are glad to see that Mr. 
Etchells further ventilated this important matter. However, the Building Research 
Board is now in being, under the chairmanship of Mr. H. O. Weller, and its reports, 
which are expected to commence shortly, will no doubt contain much of interest 
and value to the industry. 

Now that such large numbers of concrete houses are being built, Mr. 
Etchells' remarks on this subject are very timely. It can readily be conceived 
that the urgency with which the houses are required might be an inducement to 
some builders and contractors to use concrete which is not properly made or 
properly cured, but it must be remembered that no new industry can force its 
products upon the public, and this applies as much to concrete houses as to any- 
thing else. To obtain a secure footing they must be of the very best construc- 
tion, and the demand in the future will be regulated by the quality of the houses 
now being built. The porous blocks mentioned in the Address are quite excep- 
tional, and could only have been the result of bad workmanship or ignorant 
supervision, for as Mr. Etchells truly said : " If the sand fills all the voids in the 
coarser material, and the cement fills all the voids in the sand, where is the water 
to get through ? " That is the fundamental basis of good concrete, and if it is 
always gradi-d so that there are no voids and an impervious aggregate used 
there will be no complaints of its not being weather-proof. We are convinced, 
however, that the vast majority of the concrete houses now being built all over 

3 



THE CONCRETE INSTITUTE AND THE INDUSTRY. [CGNCRCTE] 

the country by reputable contractors will be a credit to the material, and a 
source of satisfaction to their owners. 

The suggestion for a special class of membership of the Institute for clerks of 
works, builders' foremen, and others engaged in a supervisory capacity is an 
excellent one, and one which we hope will be carried to fruition. The large amount 
of unskilled labour now engaged on concrete work makes it essential that those 
directly responsible for its supervision should be absolutely competent. It is no 
exaggeration to say that the success of any concrete, and especially reinforced 
concrete, building depends as much upon the careful mixing and placing of the 
materials as upon the accuracy with which the designs are followed. It is, there- 
fore, of the utmost importance that the foremen should be efficient, and, provided 
that none but fully-qualiiied men who had passed an examination were admitted, 
the formation of a body of men with what would practicalh' amount to a guarantee 
that they knew their job, and who could be unhesitatingly employed by contrac- 
tors, would be a boon to the industry and, we believe, would be welcomed by the 
men concerned as giving them a better status. 

In the latter part of his Address, Mr. Etchells referred to the arrangements 
for the acceptance as members of the Institute of Bachelors of Science, Bachelors 
of Engineering, Associates by examination of the Institutions of Civil and Mechan- 
ical Engineers and the Ro3'al Institute of British Architects, officers of the Royal 
Engineers, " or the holder of such other degree or qualification as the Council 
may determine in specific cases." We should be inclined to go further and suggest 
that, in the best interests of the Concrete Institute, some form of examination or 
test should be imposed in all cases of future candidates for membership. 

CEMENT SUPPLIES. 

The statements that have recently appeared in the press concerning an anticipated 
early increase in the supply of Portland cement is confirmed by the announcement 
of the Cement Marketing Company Limited made in another page of this issue. 

This news will be received by the interested trades with considerable satis- 
faction, as the difficulties and delays in many districts regarding cement deliveries 
have recently been at times somewhat embarrassing. 

It is generally recognised that the wide adoption of concrete for building and 
other purposes has been a feature of the post-war period and this development, 
arising at a time when there was an abnormal demand in connection with repara- 
tion work and housing, has undoubtedly added to the temporary difficulties of 
supply. Prior to the war it was possible to secure prompt deliveries of cement 
in any part of the United Kingdom, and this facility is, of course, necessarily all - 
important to concrete users. We are sure this point cannot fail to be fully appre- 
ciated by the manufacturers. 

The present announcement of speed}' relief in this direction from one of the 
principal sources of supply will, therefore, do much to remove what might other- 
wise have proved a serious objection to the adoption of concrete work in schemes 
under consideration. Given, however, assurance of adequate cement supplies, 
there will remain no serious obstacle (other than such as are general throughout 
the building trades) to the continually widening application of concrete to those 
purposes for which it is found to be pre-eminently suitable. 

The further announcement of the Cement Marketing Company, Ltd., in 
regard to the resumption of forward contracts at definite prices should tend to 
add to the stabilisation of the Building Industry. 



H 



(y 



r o- CCJNSTKUCnONAlJ 



THE "FORDSON" FACTORY, CORK 




By H. C. JOHNSON, M.C.I.t Chief Constructional Engineer, Ford & Son, Ltd. 



The ground owned by the Company (Henry Ford & Son, of the Ford Interests) 
is still known as the City Park and the Site of the Cork Racecourse, being an area 
of 138 acres alongside the river Lee, a mile from the centre of Cork City and due 
east from it on the southern bank of the river. 

It is favourably situated for both river and land service, a branch of the City 
Railways (which connects with all the broad gauge lines) entering the property, 
while boats up to 500 ft. long and with 24 ft. draught can lie alongside the wharf, a 
reinforced concrete structure originally erected for the Harbour Commissioners. 

The actual turning of the first " sod " was in April, 1917, since which time 
65,000 cu. yds. of earth have been moved to level the high portion of the site, 
a foundry, machine shop, 400 feet of retaining wall, offices, garage, canteen, 
shipping store and loading dock have been erected, the last five being temporary 
but well-built structures, while at the time of writing a power house is under 
construction. 

Fig. I, from a photograph of a model made to scale, shows the location of 
the various structures at this date, and is used each time further buildings are 
under consideration. 

The original layout for the site called for a four-storey machine shop, but it 
was finally decided that only single storey buildings should be erected, thereby 
avoiding the hoisting and lowering of medium weight castings and obtaining better 
light and ventilation. This delayed the start of erection of the machine shop 
until January, igiq, but in the meantime the 65,000 yards of excavation and 
fill, the erection of the first portion of the foundry (now an insignificant part of the 
whole), temporary offices, garage, the retaining wall and odd sheds had been com- 
pleted. Thus the greater part of the buildings shown in the general picture 
{Frontispiece) has been erected in twenty-two months. 

The ground is at two elevations, the higher — about 450 ft. wide (measuring 
at right angles to the river) — being filled ground with a surface about 2^ ft. over 
high water, and the lower of alluvial soil, with a surface about 7^ ft. below high 
water, but 5 to 6 ft, above low water, thus allowing it to drain through double 
non-return sluices. 

Foundations. — Both the higher (filled) ground and the lower (alluvial) ground 
is of a comparatively soft cheese-like nature and therefore no permanent buildings 
are erected without piles. 



H. C. JOHNSON. 



[CQNCBETEl 



Piling. — The piling has been done by Concrete Piling, Limited, of Westminster, 
on their Cast-in-Place system. Piles have averaged about 24 ft. long from ground 
to point with minimum lengths of 20 ft. and maximum of 27 ft, and, where they 
have been exposed in some cases to a depth of 14 ft., are almost perfectly cylindri- 
cal. The carrying capacity has been varied from the Company's standard of 
30 tons, determined by a penetration of not more than i in. for four four-foot 
blows of a two-ton hammer to 25 and 20 tons for i^ in. and ij in. respectively, 
using the same hammer and drop. A 10 ft. long by f diameter bar has been placed 
in the top of each to act as bonds for the pile caps. Pile groups of two to six have 
been used, with three-pile and two-pile groups predominating. 

Pile Caps. — Pile caps have been kept with tops at one foot below the floor 
line, which is the same for all buildings and is 30 ins. over H.W.O.S.T. Their 
depths vary according to load and arrangement of piles in the group. Typical 




Fig. I. Photograph of Model to Scale. 
The Ford son Factory, Cork. 



pile caps are shown in Fig. 2, together with method of design of a pile cap. In 
connection with this item the writer knows of no textbook which gives a design 
for pile caps except with a great number of piles such that conditions approximat- 
ing to plain footings might be assumed in design. This method of design is 
shown in the hope that it will suggest a study of this important item by some of 
our technical writers, and that they will evolve a compact method of design. 
It will be noted that the ground is not taken as carrying any of the load, although 
in some cases the area covered by the cap is considerable and it is because the soil 
is of a jelly-like nature, which causes the pile tube to rebound several inches after 
a blow of the hammer until the point reaches gravel at about 14 ft. on the low 
ground. The high ground, being composed of town rubbish of a very mixed 
and poor type, is little better. It has, however, one redeeming feature in the 
large amount of tin scrap punchings, which more or less " reinforces " the 
ground and thereby greatly reduces the amount of shoring to excavations — 
none being required for six feet. Because of this poor ground nearly all concrete 
flooring is reinforced, in some cases in both top and bottom layers. 



&CON5najCTKMALI 
FMr.nsir.F j > iNG ^ 



THE "FORDSON" FACTORY, CORK. 




H. C. JOHNSON. 



[CONCBETEJ 



Pile Cap Design. 
Typical yPile Group. 



Load 



Depth for Punching Shear 



Depth for Bond Bars 



45 tons 



101,000 
4X18X100 



14+2+6 



30 dia. of I bar =22^+6 



101,000 lb. 



22" 



28J 



BM 

Considering Cap as 3 beams of width 
equal to pile dia. equal to 16" ; 
each spanning pile centres ; and 
taking load conditions on each as 
average between concentrated and 
uniform distribution. 



101,000 X42 
3X5-3 



266,000 lb. in. 



Depth by B M 



V 



266,000 
III X16 



= 15+2+6 



23 



Depth for Diagonal Tension . 



Does not govern. 



266,000 



= 1-26 



Steel 



|X20XI2,000 

Bond bars fix top of pile 
22J" making 0=20" 



Bond Stress Average 



Area bars 47rX-625=7-9 

4 X -31X12,000 61 lb. per 



I — I" bars 



Bond = 



Make Cap 



7-9X31 



As shown. 



Foundry— First Portion.— This was the first permanent structure erected 
and is a steel building clothed with brickwork, 238 ft. long by 50 ft. wide and 
38 ft. to underside of trusses ; the northern 38 ft. is of two storeys, the upper 
floor being charging floor for the cupola. There is nothing of special interest in 
this structure. 

Machine Shop— First Portion.— This building is the finest, structurally, in the 
group and is distinguished by its central glass roof portion, the craneway 50 ft. 
wide, on each side of which are two spans of 33 ft. with a length of 352 ft. (16 bays 
of 22 ft.), a width of 188 ft. and nearly 60 per cent, of its exterior surface glazed. 
It has excellent light inside at any point. See Figs. 3 and 4. 



1 



CONSTBUCnON. 
ENGTNEERING 



[aEI 



THE "FORDSON" FACTORY, CORK. 



The general arrangement is shown by Fig. 5, and the outstanding 
feature is the trussed type of crane girder with diagonal members in compression 




Fig- 3- 



Tractor Assembly Conveyor and Stock Storage as seen from south end of Machine Shop. 
(Highest Output to Date — 50 Tractors per 8 Hours.) 




I'ig. 4. Machine Shop. 
Tiiii FoRDSON Factory, Cork. 



instead of being reversed and being placed in tension, the principal reason being 
that a greater shear (vertical) area is obtained with smaller section numbers, 
causing less obstruction of light than the latter condition would give. All roof 



H. C. JOHNSON. 



EQNCRETEJ 



glazing by Mellowes & Co. being of lead-covered bars, while the sashes by the 
Crittall Manufacturing Co. are Fenestra section steel. 

Machine Shop — Second Portion. — A change was made in the type of con- 




Fig. 5. Machiiie Shop Craneway. 




1 -;. ''. M.uhiiR' Shop Extension. 
The Fordson' Factory, Cork. 



struction for this addition by using northern sawtooth lights. Figs. 6 and 7 
show this structure. The roofing material on the southern slope is " Everite " 
corrugated cement asbestos on purlin centres, rather greater than suggested by 



r o, CON5TBUCtlCT>l. 



m 



THE " FORDSON " FACTORY, CORK. 



the makers, being up to 4 ft. 2 ins., this spacing being more economical than 
anything less in spite of possible smaller sections. The glazing in this case being 
also by Mellowes & Company. 




Fig. 7. Machine Shop Extension. (Shows Tractors Crated for Roimania. 




Fig. 8. Foundry E.\tension. Looking N.W. shows Octagonal Coiirnte Cohniins to Cupola Charging Floor. 

The Fordsom Factory, Cor:<. 

It will be noticed that a departure from the usual truss form of sawtooth is 
made, and for three reasons : 

(i) Delivery of the steel was quicker. 

(2) Members could not be bent in shipping, as would most likely have been the 
case with lightly built trusses, and 



H. C. JOHNSON 



ICQNCBETEi 




Fig. 9. Foundry Roof Looking south-west. (Shows Simple Roof Trusses.) 




Fig. 10. Foundry Extension. (Showing Concreting Tower and one of four Cupolas.) 
The Fordson Factory, Cork. 



f ^coNSTBucnoNAiJ THE " FORDSON " FACTORY, CORK. 

(3) The appearance is better, while the web-like maze of truss members is 
avoided. The same type of steel sash is continued in this building. 

Provision is made for the continuation of the shop by running the beams 
half-way on what are now the exterior columns, which are somewhat wider than 
the interior colrmins in consequence. 

Foundry— Second Portion.— This portion will increase the building to 
345 ft. X 270 ft. or eight times the old foundry area. 

Except for the high or two-storey northern section, in which four additional 
cupolas will be placed, the building is of the same general type as the second 
portion of the machine shop, except that bays are 24 ft. X 22 ft. instead of 
33 ft. X 22 ft. and that the sawlooth glazing is toward the east instead of the 

north. 

The high (two-storey) portion is the more interestmg structurally, smce a 
number of unusual features have been adopted. These tabulated are as follows :— 

(i) All first storey columns are of octagonal spirally reinforced concrete, 
the largest being 21 ins. in diameter to carry a load of no tons. 

{2) The floor beams are not bolted to the girders, which are not holed except 
in the bottom flanges, and only at columns, but extend beyond the double girders 
and held by a plate clip, using'two bolts. If the girders had been holed in the top 
flanges, the next heavier section would have been necessary, due to loss of flange 
section'. Furthermore, alterations take place so rapidly— due to new factory 
methods— that it is inadvisable to finally locate and fix any member of a floor 

system. 

(3) The steel roof beams are similarly treated, except that they butt on the 
centre of single girders with a connecting plate under and between them and the 
girder, while the plate clips and bolts occur on both sides of girder flange. 

Figs 8, g, 10, show the general scheme. 

(4) Bins for sand and coke run the entire length of two bays with a capacity 
of 100 tons per 22 ft., giving a total of 1,000 tons. 

(5) While steel plate floor is being placed in front of cupolas, the remamder 
of the floor is being covered with ii in. concrete slabs, approximately 3 ft. square. 
Floor loads of 800 and 250 lb. per sq. ft. are provided for in front of cupolas and 
elsewhere respectively. 

(6) The portion of roof over the bins is made of alternate sliding and fixed 
sections to allow for charging the bins. 

(7) The landing platform for pig and scrap iron on northern front has a floor 
of channels placed with webs horizontal and flanges down and I in. apart, thus 
preventing accumulation of water (having no roof) and eliminating a steel plate 

floor. 

The writer proposes to write later on the Construction Methods, Forms, 
Concrete Proportioning, Tests, Concreting Tower and Chute. 

All the buildings have been designed by the writer and members of his 
department, a number of whom are graduates of University College, Cork, and it is 
a pleasure to state that in carrying out the work by direct labour, all concerned- 
including workmen— are most interested in and proud of their work. Labour 
here is very willing and adaptable, which in a large measure induced the Company 
to locate in Cork. 



13 



ALFRED FY SON. 







^^^^ 

SHEARING STRESSES IN 

RECTANGULAR REINFORCED 

CONCRETE BEAMS. 

By ALFRED FYSON, M.Inst.C.E. 

-^ 



While wc hare much pleunurc in ijublishino thr foflowiny Ihnufihtjxd and 
original (irlicle, it must not be supposed that ve are in agreement with the conclu- 
sions arrived at, and, in point of fact, we shall he puhlishing some comments on 
the article next month which go to show that the mujoritii of specialijils have, us 
a result of their experience, come to somewhat different conclusions. — Er>. 

Before any part of the material in a reinforced concrete beam is ruptured by flexure, 
all the strains and stresses and the value of its transverse resistance can be deduced 
from and are subject to the same laws as those which govern an ordinary beam of 
homogeneous material, for like statical conditions and mechanical properties are 
common to both ; after the concrete in tension becomes ruptured to such extent that 
the internal shearing stresses become undefined, speculative or unknown, those con- 
ditions and properties no longer hold and the " true " functions of a beam are lost ; 
beyond such point then it is not intended to carry these investigations. 

The method usually employed for finding the value of the transverse resistance of 
a beam, either in a sound or ruptured state, is to neglect the effect of the concrete 
deemed to be in tension and to suppose the whole of such stress as taken up by the 
reinforcement ; the reasons generally alleged for thus eliminating the tensile value 
of the concrete being its somewhat small resisting power, compared with that of the 
material in compression, and the suddenness with which it breaks. Whatever degree 
of approximation to the actual resistance of a beam may be produced by formulae 
founded on this " elimination theory," they are certainly incapable of determining, 
even approximately, any of the actual strains and stresses induced by flexure ; such 
theory and formulae will not be employed herein, for the following investigations 
demand that all the necessary strains and stresses shall be accurately determined ; 
therefore, the required results must be obtained by rigorous mathematical treatment ; 
the concrete in tension will be made to take its due share of work, and all the material 
will be supposed to be, and to remain in, a perfectly sound state throughout. The 
computation of the external shearing forces on a beam — whether simply supported at 
one end only or at both ends — is a matter which presents no difficulty ; but the oppos- 
ing internal shearing forces and the stresses induced by them are founded on complex 
and intricate statical and mathematical principles ; the main results only of those 
principles will be dealt with here, and in a manner as simple as may be found necessary 
for their proper comprehension. 

In a solid beam of rectangular section and homogeneous material, the internal 
shearing stresses are but seldom considered in its design, for those stresses are generally 
well below the ultimate shearing strength of the material itself as found in ordinary 
practice ; but in a beam of reinforced concrete those stresses may possibly be the 
factors which tend to determine its absolute strength. Shearing stresses at a section 
may be divided into two kinds, the one of constant and the other of varying intensity ; 
the latter kind is induced when a beam is under the influence of varying bending 
moments, and is the only one which it is necessary to consider here. 

A familiar method of illustrating the effect of shear in a beam, which is often 



14 



ra-CDNSTBUCTKNAll 
[bI EMGtKEJJlNG -^ 



SHEARIXG STRESSES 



found in textbooks on the subject, is that of two or more superimposed planks ; and 
it may be briefly described as follows : — Suppose two planks, say of the same scantling, 
the first one merely supported at its ends and the second one resting on the first along 
its entire length, Fig. i. 

At the junction of the touching surfaces somewhere between the centre and a 
support, let there be marked two arrow heads, the one opposite the other on each 
plank. Now let a load W be placed any\vhere on the top surface, say at the centre ; 
the two arrow heads will become separated owing to the extension of one touching- 

W 



riG 




^^^3 



riG 



surface and the shortening of the other, Fig. ia. Suppose W to be removed and keys 
or dowels to be closely fitted into notches cut in the planks ; on W being again imposed, 
the arrov/ heads will remain in their original positions, the one opposite the other. Fig. 
IB. The addition of the tightly-fitting keys has caused the two touching surfaces to 
act together as only one, and that is due to the " shear " resistance offered by the keys. 

It is required to determine how such shear is produced, and its nature and intensity 
at any point in the length and depth of a beam. 

Theoretical determination of Shear. — Let -Fig'. 2 represent part of a side elevation 
of a beam simply supported at the ends and loaded somewhere on the top with a weight 
IF, the reaction of the left-hand side abutment being P as due merety to W, for the 



Xo 




weight of the beam itself is here assumed to be neglected. Let the beam in this 
instance be supposed to consist of some homogeneous material without any reference 
to reinforcement, its section being rectangular, the deptli and breadth each being 
supposed equal to unity. 

Let the line A\X be the geometrical axis of the beam ; let it also rcpre.sent the 
position of the plane of the neutral axis along it ; and let the line YY^ be drawn 

15 



ALFRED FY SON 



[CDNCBETEJ 



normal to X„X, cutting it at the point O. Suppose two sections to be taken, tlie one at 
aa on the line Y Y„, and the other parallel to it at bb„, the distance apart of tlie two 
sections being some small but tangible length ; and let the figure abb^a, represent a 
solid slice or strip through the breadth of the beam. 

For simplicity suppose the internal horizontal stresses due to flexure to be uni- 
formly and similarly varying for both tension and compression. Now the bending 
moment due to P is greater at the section aa„ than that at bb„. consequently the 
resisting forces or internal horizontal stresses acting against the back of the solid strip 
at aa„, are in excess of those acting against the face at bb„. Let the horizontal distance 
from the back of aa„ to the left support be called x, and the length of the solid strip 
from face to back be Ax. 

The bending moment at aa^^Px {i) 

The moment of resistance required to balance Px may be represented by forces or 
stresses enclosed by the two triangles Oac', Oa^c'^ ; the former being for tension and 
the latter for compression. 

The bending moment at bb''=^P{x -Ax) (u) 

The forces at the section bb^ resisting that bending action are represented by the 
two triangles O'bc" , O'b^c", respectively for tension and compression. 

The forces acting against the back aa„ in excess of those acting against the face 
bba are evidently the differences between the forces in the triangles Oac', O'bc" and 
Oa^c'o, 0'bfi"o ; those excess forces are due to the bending moment. 

" "px -P[x -Ax)=PAx (i") 

and are represented by the triangles Oac, Oa„c„ ; from those excess forces the nature 
and intensity of the internal shears will be deduced. So far no actual values have been 
ascribed to the forces acting against the sections 
at aa„ and bb^ as Ax has no numerical dimension ^ , 

assigned to it, nor is any such dimension ab- 
solutely necessary, as merely relative values of 
the resisting forces will suffice ; in the diagram 
Fig. 2 those relative values will be of the same 
ratio to each other whether Ax be made sensibly 
dx, or the full length x. 

This employment of a hypothetical sohd -^^ 
strip, in order to demonstrate the action of the 
horizontal direct stresses in determining the in- 
ternal shearing forces and stresses, is the method 
used by Rankine. 

Let the sohd strip abb^a^, shown in Fig. 2 
be considered as in a free state. Fig. 3, and let 
its general statical conditions be examined. 
The forces holding the strip in equilibrium are, 
an upward force P acting through bb„, a down- 
ward force of like amount acting through a„a, 

and the excess forces or stresses represented by the triangles Oac (tension) and 
Oa^Ca (compression) acting normal to the back aa„. 

Those various forces cause certain other forces or stresses through and on the sohd 
strip, some of which have to be determined. 

From any point e on the hne aO suppose a plane ee' through the sohd strip and 
parallel to the axis XX, ; the horizontal force or " pull " exerted by the excess forces 
in the triangle Oac against that part of the strip lying between a and e tending to shde 
it along the plane e'e, is there resisted by the cohesion of the material, and that cohesion 
is the horizontal shear at that plane. 

Let the sum of the forces in the triangle Oac which are acting against the strip 

16 



bo Co 




X 



riG3 



r , cr^^uc-noNAJ SHEARING STRESSES. 

from a to e be found and plotted as an ordinate q^ at the point e on the line «a„ as base ; 
then a represents the horizontal shear at the plane e'e. 

In Hke manner let the horizontal shears at other planes through the solid strip 
from a to a be calculated and plotted. By joining the ends of the ordinates so found 
the curve ;«'« of q/s is obtained. The forces in the triangles Oac, 0«,., may be 
summed either from ; or a„ as origin, but whatever sign is used to commence with must 
brchan^d at he neutral axis, as the forces there alter from tension to compression. 



or vice versa. 



Suppose the summing to be commenced at a, then q=o at the origin. Midway 
between a and O 7=thre^e-fourths of the area Oac ; at O, ,,=the area 0«. ; midway 
betreen O and a'the ordinate , =the area Oac less one-fourth of the area Oa^c 
and at a q =the area Oac less the area Oa^c„ that is=o. In the present mstance the 
curve aaW q/s is evidently a parabola and its ordinates represent the horizontal 
<.hPflrs at all points throughout the solid stnp from a to a,. , • .^ a, 

^smple method for finding the internal horizontal shears havmg thus been 
descrtbed ft is now necessar^^ to determine the correspondmg interna vertical shears 
and Jhey depend on the following principle :-" The intensities of the tangential 
Jtlses It a given point on a pair of planes at right angles to e^ch o«ier and to th 
Plane paraUel to which the stresses act are necessarily equal (Rankme). Iheretore 
Se cu^e aa'. of q/s not only serves to give the values of the hori-ntal, but also those 
of the vertical shears at the same points. Those values which will now be called 
° restive "as they may not always be actual values, must be transformed into real 
mtenlries of the ta^ngential stresses ; and it ^vill be necessary to take into consideration 
not onlTtl- value of P acting at the required section, but also m a general sense the 
depth H and breadth B of the beam at that section. 

^InpTi let the solid strip abKa„ be supposed to act as if it were still a part of he 
beam as £ Fig. 2. The total vertical shear can only be that due to P and as the 
relarive vSues of the horizontal and vertical shears at the section a« are identical and 
each iindTs represented bv the curve of q/s, so by putting the area of the figure aaaa 
equal op'b will those relative values be changed into real values and when the 
depth nfs taken into consideration the actual intensities of the tangential stresses at 
Jl'p^il of te section will be given. Let such intensity of the ^^^^^^ 
any'^point be called , and let the mean value of the q/s be called ,„ In F. . 3 tne cun^e 
aa'a^is a parabola, Oa' is equal to 3^„-2, and aa, is equal to H , hence the follo^^mg 
identities are found : — 

The area of aa'aaa=l{Oa' Xaa/)—— 

As Oa'=^^ then q„, = — V . . . . i^v) 

P -x 
Now q : ^ : : q-y. q„, 

Pqr .... (I) 

Whence 9=^^^ 

The maximum intensity of the tangential stress is at ^he neiitral axis^ and when 
the curve of q/s is a parabola its value is generally expressed as .that of t e mean 
IntenTy on the entire section. When therefore. ,„ is once found it is seen that any 
reniiired a can b5 easily determined. ^ ^„a 

' Xbraic formul Jcould readily be given for fi„d,„g .he value of any ,^d 
thev would be simple expressions tor the elementary example l'>^*J'^"'^'t: 
t7 sZ tormul. would 'not apply to reintorced ""Crete where al hough the 
general meth<Kl of determining the stresses .s s.m.lar to that g.ven m 



ALFRED FY SON. 



iCDNCBETEJ 



above, the particular formula" defining them would be somewhat different and more 
complex. 

Reinforced Concrete Beam. — As the computation of the shearing stresses in a 
beam of reinforced concrete is then not so simple as for a beam of homogeneous material, 
it has been thought expedient to compute in practical and numerical detail those 
stresses as deduced from an actual example, the required formula; and symbols being 
supplemented by their proper numerical equivalents. 

The beam chosen for example is shown in section, Fig. 4 ; other general particulars 
not there given are— length over all, 10 ft. ; span, 9 ft. ; weight, 900 lb. ; age when 
tested, four months. 

This beam was one of several tested by Dr. Oscar Faber, and was described 
by him in Concrete and Constructional Engineering, of May, 1916 ; it is chosen 
here because some of the tests appear to be well suited for these present require- 
ments. 

One of the tests made was for the purpose of discovering at what load the first 
ascertained crack appeared, that is when the concrete was first ruptured by tension ; 
that rupture apparently occurred when the load applied at the centre of the beam 
reached 4,100 lb. 

The bending moment at the load, including the moment due to the weight of the 
beam itself, would be nominally about 127,000 inch lb., but the beam did not rest on 
" knife edges " nor on frictionless supports ; making some allowance for the lack of 
such conditions and also for the fact that the first rupture sometimes takes place 
before it is observed, the following particulars in (2) may be assumed as approximately 
correct when the first crack in the concrete actually occurred. 



(Bending moment at the centre of the beam . . 117,000 inch lb. 
(Outside shearing force at the centre of the beam 4,100-^2=2,050 lb. 



)■ 



(^) 




Fig 4 

2 - 1 diifjteeL roc/j 



The computation of the internal stresses may prove to what extent — if any — this 
outside shearing force of 2,050 lb. contributed, by its induced shearing stresses, to the 
first rupture of the concrete. 

Moment of Resistance of the Beam {Fig. 4). — From what has been previously 
expressed as to the resisting effort of a beam 
subjected to flexure, it may be correctly inferred 
that all the material in it will be made to yield 
its natural resistance, and that all. the internal 
horizontal stresses throughout the depth of the 
beam will enter implicitly into the calcula- 
tions. Therefore, the whole of the concrete in 
tension will be subjected to strain, as a proper 
appreciation of the shearing stresses and others 
depending on them cannot be otherwise obtained. 

The method adopted for finding the moment of resistance at some required section 
of the beam is— with some slight modifications— in accordance generally with that 
described in Concrete and Constructional Engineering, Vol. viii., Nos. 5, 6 and 7 ; the 
details of the calculations will not be given herein, but only those results defining the 
internal horizontal stresses, and other particulars which will be required subsequently : 
thus in (3) will be found the maxima stresses relating to the moment of resistance 
necessary to balance the bending moment of 117,000 inch lb. as given in (2) ; those 
maxima stresses are believed to be in close accordance with reaUty, but some moderate 
difference either more or less, would not affect the explanations of the general principles 
involved. The following particulars relate principally to Fig. 5, and to the moment of 
resistance of 117,000 inch lb. : — 



fa, CONSTBUCnONAlJ 



SHEARING STRESSES. 



Concrete in compression . 
Concrete in tension 
Reinforcement in tension 
Sectional area of reinforcement 



Position of the neutral axis 



f„ G25 lb. per sq. in. . . a^Cg 

f 295 lb. per sq. in. . . ac 

f, 5840 lb. per sq. in. . . . 

A^ 0-8836 sq. in. .... 

h„ 5 80 inches from top of beam. 



(3) 



If, fo, fs ■ ■ • any horizontal stress at lb. per sq. in. respectively for 
the concrete in tension, the concrete in compression, and the steel 
reinforcement in tension. 

Practical Determination of Shear. Beam {Fig. 4) . — The diagram Fig. 5 is a part side 
•elevation of the beam, the transverse section under consideration being on the line 
1'1'„, its neutral axis being at O through which is drawn the horizontal line X„X. 

In what follows with respect to the formation of the curve of q/s, the aid of the 
solid strip as in Figs. 2 and 3, will not now nor hereafter be further employed ; the 
actual horizontal stresses w-hich are acting at the section, and which constitute the 
moment of resistance necessary to counterbalance the bending moment there, will be 
substituted for the previously undefined horizontal stresses which were supposed to be 
acting against the solid strip. Such method is theoretically and practicallv correct in 
a beam where the stresses are uniformly varj^ing and may be taken to be if not theoreti- 
cally yet practically correct in a reinforced concrete beam in which the stresses are not 
uniformly varying. In the figure, the weight of the beam between the line of action of 
P and the section at aa^ is supposed to be neglected. 




J pq MP -top 0(fCI d^ J^ 106 

Jca/efor ftorijortla/ Shears 



riG 5 



In Fig. 5 the horizontal stress intensities are represented by ordinates drawn from 
the base line aa„ to the curves Oc„ and Oc'c, the former for the concrete in compression, 
the latter for that in tension ; the stress intensity for the reinforcement is represented 
by the rectangle hb' the depth of which is \ inch, that being d the diameter of each rod. 
In the diagram tlie stresses on the concrete are those due to each one inch breadth of 
beam, and in order to make the total stress on the reinforcement conform also to that 

19 



ALFRED FY SON. [CDNCBETEl 

breadth it must be averaged by dividing it by B. The geometrical centre of the 
reinforcement is supposed to be also the centroid of strain. 

M. 4(5840X0-8836) „^ „ 

.-. Length bb' = '-'--'=^- ^—•^^ = 860 lb. per sq. mch . . 4) 

^ dB 3X8 f n \fi 

All the horizontal stress intensities are now complete for the construction of the 
curve of q/s, but for certain reasons which will appear subsequently, the effects due to 
the concrete in tension will be kept distinct from those due to the reinforcement. 

Suppose the summing of the stresses to be commenced at a^. As Oc„ is drawn in 
as a straight line — its real divergence from a straight line being too small for practical 
purposes — the stresses in compression are therefore uniformly varying, and the 
relative value of the horizontal shear at the neutral axis is 

/A^^^,>ao^625X5;8o^^g^^^ ^^ 

^22 2 

Plotting that quantity it is represented by the ordinate Oa'„ ; the remainder of 
the curve of q/s between O and a^ is easily drawn in as it evidently forms part of a 
parabola. 

Next, commencing at a for the stresses on the concrete in tension and successively 
summing the ordinates to the curve cc'O from a to O, the ^^'5 so found and plotted are 
delineated by the curve aa'a" ; lastly the area of the rectangle of stresses — that is 
8O0 lb. X 1=645 ^b. — due to the reinforcement is added to the curve aa'a" ; the value 
of any q^ for total " tension " effects is then given by an ordinate to the curve aa'a\ its 
base being the line aO. 

The method of summing the stresses from separate origins has certain advantages 
in the present instance and is in general perfectly correct, for the total stresses in com- 
pression must balance those in tension ; in the present case each total quantity is repre- 
sented by the same ordinate Oa\. The actual intensities of the tangential stresses at 
any points in aa^ can now be determined after q^ has been computed. For the beam 
under consideration the value of q^ — that is the mean ordinate of the curve aa'a\a^ — 
is thus found : 

_area^aV^„_i4o4_4_^^^^ ^^ ^^^ 

^'^ length aa„ 12 ^ ' 

The value of q^ at the neutral axis is given in (5) as i8i2'50, consequently the 
intensity there of the tangential stress is, by equation (i) : 

Pq, 2050X1812-50 ,^ . ^ , ^ 

= -— -—=— =3i'93 lb. per sq. mch .... (7) 

^ BHq^ 8X12X1212 ^ ^^ r -L 

In a similar manner the stress intensities at other points in the depth of the beam 
may be computed, but near to the reinforcement there is a local concentration of stress 
set up, which in some cases might prove to be of importance, as will now be shown. 

Local Concentration of Stress. — On the line ee' Fig. 5, just above the reinforcement 
the q^ to the curve aa'a\ is found to be 1,195 lb. ; it is divisible into two parts, one of 
which is due to the concrete alone and equals 550 lb., and the other is due to the 
reinforcement alone and equals 645 lb. 

From equation (i) the stress due to the whole amount of 1,195 lb. is : 

2050X1195 ,, . , , . 

g = z =21-05 lb. per sq. inch (v) 

^ 8x12X1212 J ±^ -1 

21-05 X550 

The stress due to concrete alone then = =9-69 lb. per sq. mch 

1195 

■ ivi) 
21*05X645 • , 1 

The stress due to reinforcement alone then^ ^11-36 lb. per sq. mch 

1195 ^ ^ ; 

Now the stress — 11-36 lb. per sq. inch — due to the reinforcement is the average 



I&^?d^;g!^j.^^ SHEARIXG STRESSES IN CONCRETE BEAMS. 

stress as if taken over the full breadth of beam ; it seems reasonable to suppose, 
however, that there must be a greater intensity of stress just over the rods than at the 
extreme sides of the beam. The precise determination as to the actual distribution of 
those stresses over the breadth of the beam depends no doubt on the spacing, size and 
form of the reinforcement; it is a matter of considerable complexitv, and will not be 
attempted here ; but from certain calculations which have been made for present 
purposes it would appear that for the beam under examination the maximum intensity 
of the shearing stress just over each rod as due to reinforcement alone is about twice 
the mean intensity as if taken over the entire breadth of beam. 

Therefore, just over each rod the maximum shearing stress on the concrete would 
be, from {vi) : 

^=g-69 + (2 Xii-36)=32-4i lb. per sq. inch (7A) 

It is thus seen that a local concentration of shearing stress intensity has been set 
up at the reinforcement which is greater than that found at the neutral axis in (7). 

{To he- concluded.) 



THE TALLEST ALL-CONCRETE BUILDING IN THE 

WORLD. 

A BUILDING of great interest to reinforced concrete engineers is now being erected 
at the corner of Frankfort and Gold Streets, Manhattan, N.Y. 

Standing in the heart of the Leather District, it is to be a modern up-to- 
date office building, seventeen storej^s high. 

It is being built for the Hide & Leather Realty Co., a real estate association 
formed by a few prominent leather merchants, desirous of procuring comfortable 
quarters for themselves and at the same time providing suites of offices for other 
companies in the vicinity. This structure will provide a turning point in the 
history of architecture and reinforced concrete engineering, as it is the first high 
office building to be built entirely of concrete, both as regards interior frame 
and exterior walls. 

The facing, instead of consisting of brick or stone, is concrete, a radical 
change from customary practice for a building of this type. When completed, 
it will have the distinction, we understand, of being the tallest all-concrete 
building in the world. 

There are several new and interesting features in its construction, and it 
will probably be the Mecca of reinforced concrete engineers throughout the 
I'nited States. 

Our illustration on page 34 will give a good idea of the artistic appearance 
of the building, and shows what can be done architecturally with concrete. 

Messrs. Thompson & Binger, Inc. of New York and Syracuse, are the designers, 
engineers and constructors of the building. 



LIVERPOOL HOUSING SCHEME. 



rCQNCBO'El 




CONCRETE COTTAGE BUILDING. 
HOUSING AT LIVERPOOL. 



The question has been asked from time to time, why is it not possible to organise 
house production on the same broad comprehensive hnes that made it possible 
during the war suddenly, not only to produce munitions for our own vast army, 
but also, to some extent, for those of our allies. There are many reasons why 
it is not altogether possible to organise for production in peace time with the 
equal speed and intensity that can be maintained in a time of great national 
danger. Moreover, in time of war, econom}^ is a matter that must always be 
sacrificed to expedition. There is, however, no reason why some of the methods 
of organisation that were everywhere employed on large constructive works 
should not — with certain adaptations — be employed with success on housing 
schemes of sufficient magnitude to make such methods possible. 

At Liverpool the opportunity exists, and advantage has been taken of it. 
The first contract on the Garston estate is for 2,000 houses to be completed by 
the middle of 1922, and this is to be followed by a further 4,000, covering in aU. 
more than 500 acres. The contractors are the Economic Building Corporation. 

The work was begun in June of last year, and in spite of the bad weather 
of July and August the contractors claim to be ahead of the scheduled time. 
When building was begun it was with twenty-two men, and £10,000 were spent 
in the first four weeks. The number of men has now increased to nearly 1,100 
and the amount spent to £25,000 to £30,000 each week. 

ORGANISATION AND WELFARE ARRANGEMENTS. 

The work that is in progress includes, in addition to 700 houses which are 
in various stages of completion, a welfare department for the men, a large canteen 
which, when finished, will accommodate two billiard tables, reading, WTiting 
and games' rooms, and model kitchens capable of serving from 1,200 to 1,400 
meals in a quarter of an hour. The cost of building and furnishing the canteen 
is some £17,000. It has also been necessary to provide sleeping accommodation 
for some 400 men. In connection with the club premises that are erected for 
the men, their welfare is considered to a further degree that does infinite 
credit to the organisers. The welfare department, when completed, will include 
a resident doctor and a complete Red Cross establishment. Already playing 
fields have been acquired — these will afterwards form a public recreation ground 
— and dressing-rooms erected thereon. In connection with the club, evening 
classes are organised provided that the demand for any particular subject is 
sufficient. A large number of the ex-Service workers have applied for a class 
on modern house construction. 



&^?.Sg^Ng^ LIVERPOOL HOUSING SCHEME. 



About forty miles of light railway have been laid on the site. Other important 
items are a large factory that is in course of erection for the manufacture 
of the blocks ; this will enable the work to proceed irrespective of the outside 
temperature, there are also standard joinery workshops, stores and administra- 
tive offices. 

An interesting point is the amount of ex-Service and unskilled labour that 
is being employed in the manufacture of the blocks. Eighty-five per cent, of 
the workmen are ex-Service men, 90 per cent, of whom are unskilled. All the 
work, however, is subject to the most severe and thorough supervision by experts. 

Enough has been said to indicate the magnitude of the job. The suggestion 
of war organisation is further emphasised by the presence of a fleet of old Army 
lorries and motor buses that are used to convey those men, for whom accommo- 
dation is not provided on the job, to and from their homes ; moreover, ammunition 
wagons are used on the site as labourers' carts, and various Army huts have 
been erected — huts that have seen service as far afield as Mesopotamia. 

MATERIALS. 

There is no doubt that to-day concrete is the ideal material with which to 
build on such a job, for it means that the organisation can then embrace not 
only the actual erection of the houses, but the manufacture of the building unit. 
Owing to the present uncertain delivery of bricks it would be utterly impossible 
to obtain the same efficiency of output on a job where the men knew that at any 
moment, if the supply of material ran short, they would be turned off at the end 
of the week. 

CONSTRUCTION. 

The system of construction, which is that of the patent of the Economic Build- 
ing Corporation, is one of hollow concrete walling. The internal and external por- 
tions of the wall are formed with a T-shaped block (see Fig. i. Block A). This 
block has a tongue on the top edge and a corresponding groove on the lower, 
and a projecting nib. It is all cast in one piece. The nibs bond and the courses 
are " staggered." Special plate and joist blocks are designed to distribute the 
load evenly over the wall. There are various standard blocks for different parts 
of the building. " B " {Fig. i) is a block for windows, doors or other openings, 
linings, heads, lintels and sills. " C " is for sills, steps, plates, angles, string- 
courses and foundations. 

The aggregate for the outer leaf is gravel, specially selected and graded, 
while for the inner leaf clinker blocks are used. Originally the blocks for the 
outer walls were made by the Economic Building Corporation in their own special 
aluminium moulds on the wet system. This — as we have had occasion to note 
elsewhere — although an extremely satisfactory method of block manufacture 
is not particularly expeditious. These moulds were therefore discarded in 
favour of Winget pressure machines, which have been specially adapted for the 
manufacture of these blocks. Thirty-two of these pressure machines are now 
installed on the job (see Fig. 2). They are organised in batches which are served 
by a Winget chain spade concrete mixer. There are twelve of these mixers 
employed on the job and three crushers, also made by the above firm, of different 
kinds. An idea of the rapidity with which the work of block making proceeds 

D2 23 



LIVERPOOL HOUSING SCHEME. 



(CONCRCTH 



Block A 




2 /fib. 



Fig. I. Types of Blocks used. 



Block B 






/2 




'2 



Block C 



^-S. 





Fig. 2. Some of the Block-making Machines. 
Housing Scheme, Liverpooi-. 



24 



i 



CON.STRUCTIONAL 
ENGINEERING — ; 



LIVERPOOL HOUSING SCHEME. 



may be gathered from the fact that, on an average, slabs of all kinds necessarv 
to complete five houses from start to finish are made each day. Other mechanical 
appliances on the job include a Winget wagon loader and elevators, both of which 
save a very considerable amount of labour. Fig. 3 shows one of these elevators 
at work, expeditiously superseding the labourer with his hod. 

Fig. 4 shows the special factory, nearing completion, in which it will be possible 
to manufacture the blocks in all weathers. Fig. 5 shows some of the blocks 




Fig. 3. Showing Elevator in Operation. 

HOI'SINC SCHEMT, LIVERPOOL. 

for the outer walls stacked on the ground ; Figs. 6 and 8 show houses in 
•course of construction and completed. 

The whole housing situation at Liverpool is one of particular interest, for 
the town has long been known for its pioneer work. The present estimated 
shortage of houses is 15,000. Towards making good this deficiency some 1.224 
acres of land have been acquired, and layout plans have already been prepared 
for more than half this area and contracts have been let for making the roads 



25 



LIVERPOOL HOUSING SCHEME. 



[CONCRETE] 




Fig. 4. Block-making Factory. 
Housing Scheme, Liverpool. 




Fig. 5. Stacking Ground. 
Housing Scheme, Liverpool. 




Fig. 6. Hdu^is uiuk-r Construction, Garston Estate. 
Housing Scheme, Liverpool. 



26 



r »^ CONSTPUCTIOTMA 
Lt^ EJWGINEEJJING 



m 



LIVERPOOL HOUSING SCHEME. 



and sewers, so that this land is now available for 10,000 to 12,000 houses. 
Contracts have been let for 6,300 houses, including a direct labour scheme. 
Two hundred and six houses are tenanted, and in addition there are complete d 
and occupied 484 temporary dwellings. Work is now in progress upon 1,608 
houses, making a total of about 2,300. 




Fig. 7. Layout Plan — Springwood-Allerton Estate. 
Housing Scheme, Liverpool. 




Fifj. .S. Fiuishril Ilui ., (,,a t..ii Fstatc. 
Housing Scheme, LivERrooL. 



On the Garston estate there are five types of house plans in use ; these are 
further varied in appearance by grouping and by the addition of gables and 
similar features which break the frontage and roof line. They are all parlour 
type houses. In many housing schemes at present in progress it has been found 



27 



LIVERPOOL HOUSING SCHEME. 



[CDNCKETEJ 






28 



^ 



/^^""d^^^i^^ LIVERPOOL HOUSING SCHEME. 



difficult, owing to the high cost, to provide many of the small additions that do 
so much to simplify the daily routine of housework. 

At Garston there are to be found many small improvements. For example, 
a combination dresser. is installed in the living-room, which is also fitted with 
bookshelves and a folding desk. Linen, boxroom and cupboard accommodation 
has received careful consideration. Gas cookers are installed and electric light. 

The houses have all been designed by Mr. F. E. G. Badger, A.M. Inst. C.E., 
who is the Director of Housing at Liverpool. Fig. y shows the lavout of the 
Garston Estate, or the Springwood-AUerton Estate, by which name it is also 
known, and certain types of house plans which are being used on the estate 
may be seen in Fig. g. It will be noted that a considerable amount of space 
is devoted to allotments and open spaces. 

Finally, an idea of the determination with which the Economic Building 
Corporation are facing their task may be obtained from the fact that in order 
that the work may proceed steadily throughout the bad winter weather, in 
addition to the factory for block making, the men of the outside trades are being 
supplied with oilskins, and it is proposed to provide fabric coverings for some of 
the houses in course of erection. 

MEMORANDA. 

How to Obtain Watertight Concrete. — Where watertight concrete construction is 
desired, particular attentiou must be given to the method of proportioning, and the 
method of mixing and placing of the concrete. Care should be taken to ensure the 
proper bond between the different batches of concrete or between the work done on 
different days. This does away with leaky seams or joints. When it is necessary to 
stop work, the new concrete, when work is resumed, should not be poured before the 
previously placed concrete has been especiahy prepared by roughening in some wav 
and painted with a coat made of neat cement and water.- — Concrete, U.S.A. 

Reinforced Concrete Bridge : Regent's Canal. — A piece of work which is of some 
interest, owing to the conditions under which it has been done, is the construction of a 
new reinforced concrete bridge over the Regent's Canal, near York Road, King's Cross. 
This bridge forms part of a scheme to provide a new entrance from Wharf Road to the 
Great Northern Railway Company's goods yard, which includes the provision of new 
approaches, and the demolition of the old steel bridge over the canal. 

Owing to the necessity' of not obstructing the canal, it was found impossible to 
construct this bridge in place, as the necessary shuttering and supporting timbering 
would have reduced the headway and waterway width below tlie permissible limit. It 
was therefore decided to construct the three girders of the bridge independently and 
afterwards place tliem in position. Tlic girders were accordingly built on shore, in line 
with their proper positions, and when finishefi each was lifted on to two four-wheeled 
trucks. When they were ready for launching, one bent of piles was driven in the fair- 
way and a track laid on temporary girders thrown across the canal. The girders were 
tlien launched in succession, and on being carried over were jacked and lowered into 
position after the removal of the temporary gear. The operation was quickly accom- 
plished and the headway was not obstructed at all, while the one pile-bent reduced the 
obstruction of the waterway to a minimum, both in the matter of actual width and 
length of time. The centre girder weighed 50 tons. The span is 45 ft. Once the 
three girders were placed, work was commenced on the flooring in place. For this, 
shuttering hung from tiie top side of the girders was employed, sotiiat nothinginterfered 
with the full head room for canal traffic. The work has been carried out by Messrs. 
Sir Robert Mc.Mpinc & Sons, Westminster, S.W., for the Great Northern Kaihvay, 
under tiie supervision of the latter companvs engineer, Mr. C. J. Brown, C.B.E., 
M.Inst.C.K. 

29 



//. J. BIRNSTINGL. [QQNCPETE] 



THE TREATMENT OF SMALL CONCRETE HOUSES. 

By H. J. BIRNSTINGL, A.R.I.B.A. 

The relationship between the form of a building and the -material from which it 
is built, the extent to which the latter does and should control the former, is a 
matter that has repeatedly occupied the attention of those who desire to formulate 
the various and diverse qualities that characterise good architecture. At some 
time it has been insisted that the intimacy of this relationship should be made 
one of the most important tests, at others it has been thought that the outward 
form of a building is all with which it is necessary to be concerned. In addition, 
however, to the relationship of form to material, that of form to purpose and 
of construction to ornament should be acknowledged, since they too constitute 
tests with which it is not possible altogether to dispense in an attempt at 
architectural assessment. 

To observe how these relationships varied in the different great styles of 
architecture would constitute a research of rare interest. As a superficial general- 
isation, it might be said that there was this difference in the decadence of certain 
of them. The decay under the Roman Empire was an abuse of ornament, charac- 
terised by its useless and unrelated profusion. The decay of Gothic was an abuse 
of material ; stone used as if it were wood, or even metal. The decay of the 
Renaissance was an abuse of form ; the classic elements deprived of their real 
use and significance and robbed of their virility by being assigned to tasks un- 
becoming to their origins. 

The last two years have witnessed a determined attempt to alleviate the 
housing shortage by the use of a material that has hitherto been used almost 
exclusively — in England — on larger works. At the present time cottages are 
being built of concrete in almost ever}' part of the country. For the most part, 
considered purely as contrivances of protection against the elements, the results 
are satisfactory, but the complex nature of man demands more from a building 
than that it should perform, in the very crudest way, an absolutely utilitarian 
function. Consciousl}^ or unconsciously, he requires an aesthetic pleasure ; the 
pleasure that is yielded by colour, form and texture, and it is the failure to supply 
these that has caused the concrete cottage to be regarded with obloquy. The 
questions naturally arise : Must concrete cottages be dull ? Should they endea- 
vour to follow the traditional lines of cottages built in other materials, or should 
they evolve a new form which is the outcome of the particular qualities of the 
material ? To the first of these questions it is easy to reply. There are no more 
inherent reasons why a concrete cottage should be dull, than there are for a brick 
cottage. Yet a dull brick cottage is unfortunately an all too common pheno- 
menon. The second question, however, is one requiring much consideration. 

In the first place the methods of using concrete vary to a greater degree than 
is to be found with most other building materials, certainly more than is the case 
with brick or stone. It is only necessary to point to such diversities as concrete 
block construction, monolithic construction and the gunite house in order to 
realise that these diversities are, indeed, so great as to make it appear that different 
materials, rather than the same material differently handled, are being employed. 
It will thus be apparent that, where the new material most nearly approximates 
to an existing one, any change in form or treatment will be less marked, than where 

30 



f^^?^?i^I^^ TREATMENT OF SMALL CONCRETE HOUSES. 



a new material constitutes a radical departure from the normal. Thus it may be 
expected that the concrete block house will not depart so completely from the 
generally accepted forms as the monolithic house. 

Where bricks of an inferior quality are used it becomes necessary to apply a 
protective coating in the form of a rendering or of a rough cast ; the concrete 
block is similarly used, where the aggregate is sufficiently good to produce a block 
that will withstand the weather, and that will present a good appearance, both as 
regards texture and colour, the joints are pointed and a fine and pleasant wall is 
produced. Where, however, an aggregate is used that will not produce a block of 
such fine quality, it is necessary to resort to rough casting or similar treatment. 
Figs. I and 2 show some concrete block houses at Chepstow designed by Mr. 
Henry E. Farmer, F.R.I.B.A. It will be seen that in Fig. i the outsides of the 
houses are rendered and the treatment is very similar to that of a brick house 
on which facing bricks are not used. Fig. 2 shows a pair of houses nearing comple- 
tion on which the concrete is not faced. In connection with this illustration two 
points are worthy of consideration. In many houses the appearance is completely 
marred by the employment of too large a block. The result cannot be satis- 
factory where the unit is altogether out of proportion to the size of the building ; 
the unit must be in scale, otherwise windows, doors and other features lose their 
relative values. The second point to be noticed is that no attempt has been made 
to imitate stone work ; it is easy to cast a block on a pallet so that a vermiculated 
hammer-dressed, or other similar face is produced. Nothing is more contrary 
to the canons of good taste than that one material should endeavour to insinuate 
itself in the guise of another. The surface of the block will depend chiefly upon 
the aggregate that is obtainable. At Chepstow local stone chippings were largely 
used ; this, as might be expected, will produce a more pleasant facing block than 
would result in districts where destructor clinker was the only available aggregate. 
Fig. 3 shows a bungalow built on a patent system of construction which divides 
the wall surface into bays by means of projecting piers. The surface of this 
bungalow is rough casted, and the projection of the piers is here a distinct advan- 
tage to the design, because these vertical lines are emphasised by the proportions 
of the windows. It is just upon such small matters that success depends. It is 
but necessary to substitute, for a moment in imagination, long low casement win- 
dows and the charm, the " rightness " of the design disappears. It is true this is 
but a matter of architectural composition, but with the concrete cottage it is 
unfortunately one that so often receives insufficient consideration. It would 
seem, then, that the concrete block house makes no particular demand upon 
the designer. The usual limitations will apply, such as local resources, the sum to 
be expended, accommodation to be provided, and it is these factors, rather than 
any new and startling qualities of the material, or method of using it, that will 
govern the design. 

From the concrete block we pass on to the consideration of other methods 
that proceed farther into the unknown. For the most part steel is not required 
in cottages, the loads to be dealt witli being small. Steel- framed, concrete-covered 
houses have, however, been erected in various parts of the country, but their 
success, considered financially, depends almost entirely upon standardisation of 
the parts. A standardised steel frame leaves very little scope for diversity in 
design. If the design be good, it may well be worth repeating, but good architec- 
ture cannot flourish under such Hmitations. There is no advantage in construct- 

31 



//. /. JilRNSriNGL. 



[CQNCBETEJ 



ing cottages by means of a steel frame unless they can be l)uilt more cheaj)ly than 
other materials, and it will only be possible to build them more cheaply if the 
component sections are standardised. The only freedom left to the designer, 
therefore, is in the matter of fenestration, details of cornices, eaves, door hoods, 




Fig. I. Houses at Bulwark, Chepstow. 

\Architect: Henry E. Farmer, F.R.I .B. A. 




Fig. 2. Houses at Bulwark, Cukpsthw. 

[.irchitect : Henry E. Farmer, F.R.I.B.A. 



■surface treatment, and it is inevitable that most architects would, quite rightly, 
chafe under such restrictions. That, however, the steel frame house is capable 
of yielding delightful results is shown in Fig. 4, which is a house at Dormanstown 
designed by Messrs. Adshead & Ramsey and Prof. Patrick Abercrombie, but its 



32 



r *, CONSTKUCTlC»<JAlJ 
\Ci. ENGIMFXRING -~-J 



TREATMENT OF SMALL CONCRETE HOUSES. 



success depends upon a fine knowledge of architectural design. The limitations 
imposed by the steel structure have been turned to the very best account. The 
same skeleton framework in the hands of a less experienced person, and one who 
had not studied and assimilated the traditions of English architecture, would have 




Fig. 3. 



\ Six-Roomed Bungalow, Banstead. 

[irchiiect: H. D. SeaUs Wood, F.n.J.B.A. 




1-U. 4. HOLSIIS AT DORMANSTOWN. 

Architects : Messrs. Adshcad, Ramsey, and Pro/. Patrick Abcrcrombie. 

resulted in a building of the utmost dullness, bereft of all charm and character. 
We are now led to the consideration of another aspect of our subject . tlie 
suitability of a particular architectural composition to its surroundings, bot 1 
natural and arcliitectural. There is no doubt that in rural districts and in small 
towns— in contradistinction to large cities-a certain harmony is to be noted 



H. J. BIRNSTINGL. 



[QONCBETEJ 



between buildings and their natural surroundings, since local materials were so 
largely used. In stone districts, the local stone emphasises the prevailing tone 
in the landscape. The shape of a building, too, will often, in some quite subtle 
way, bear a relation to the character of the country, crouching into the ground, 
as it were seeking protection, or aspiring upwards, and seeming to reiterate the 
prevailing lines of trees or cUffs. Such things as these cannot be neglected even 
when designing in concrete. Thus it should at once be appreciated that a house, 
such as is illustrated in Fig. 4, has a suitability that is limited by environment and 
position. Lack of consideration of this matter might lead to condemnation of 
the design by the layman or by a hostile critic of concrete construction, although 
the fault does not lie intrinsically with the design. And this aspect of the problem 
assumes even greater prominence in considering monolithic construction, which 
lends itself to quite unusual forms which may offend in certain juxtapositions yet 
please in others. ^^^ ^^ concluded.) 




BUILIIING lOR THI. lllDi: AN'II I, I:\IH1K ReALTV CO., MANHATTAN. 

[See page 21.) 



34 




THE CONCRETE INSTITUTE. 



THE CONCRETE 
INSTITUTE. 



MONTHLY NOTES, 

By the SECRETARY. 



The American Concrete Institute will be holding its Annual Convention in Chicago 
on February 14, 15 and 16, 1921. 

Their President has extended a cordial invitation to such of our members 
as may happen to be in America at the time. 

In extending this invitation he adds that doubtless the two Institutes will 
find mutual advantage in the discussion of problems equally affecting both 
Institutes. 

It is hoped that our members will shew their appreciation of this act of hos- 
pitality by taking advantage of the President's kindness. 

THE ANNUAL DINNER. 

The Annual Dinner of the Concrete Institute was held in the Venetian Suite, 
Holborn Restaurant, London, on Thursday, December 9, 1920. The President, 
Mr. E. Fiander Etchells, A.M.Inst.C.E., A.M.I.Mech.E., Hon. A.R.I.B.A., etc., 
was in the Chair. Amongst those present were :— Mr. J. W. Simpson, Member 
Corr. de I'lnstitut de France, President of the Royal Institute of British Archi- 
tects ; Mr. W. B. Worthington, B.Sc. (Vict.), Vice-President of the Institution of 
Civil Engineers ; Rev. S. A. Alexander, M.A., Canon of St. Paul's Cathedral ; 
Mr. G. Topham Forrest, F.G.S., F.R.I.B.A., Hon. M.C.I. , Architect to the London 
County Council ; Captain H. Riall Sankey, C.B., R.E. (ret.), M.Inst.C.E.. Presi- 
dent of the Institution of Mechanical Engineers ; Sir Charles T. Ruthen, O.B.E., 
F.R.I.B.A., M.C.I., President of the Society of Architects ; Major J. Wightman 
Douglas, D.S.O., R.E., Commissioner for Special Construction, Ministry of 
Health ; Mr. C. Le Maistre, A.M.Inst.C.E., M.I.E.E., Secretary of the British 
Engineering Standards Association ; Mr. T. J. Gueritte, B.Sc, Ing. E.C.P., 
President-Elect of the Societe des Ingenieurs Civils de France ; Mr. Norman 
Scorgie, M.Inst.C.E., Vice-President of the Institution of Municipal and 
County Engineers ; Mr. Arthur Crow, F.R.I.B.A., President of the District 
Surveyors' Association ; Mr. Bernard Dicksee, F.R.I.B.A. ; Mr. G. Springfield, F.J.I., 
President of the Institute of Journalists ; the following Vice-Chairmen :— Sir 
Henrv Tanner, C.B., I.S.O., F.R.I.B.A., Past-Pres. C.I. ; Mr. F. E. Wentworth- 
Sheikls, O.B.E., M.In^t. C.E., Past-Pres. C.I. ; Mr. H. D. Searles-Wood, F.R.I.B.A., 
F.R.San. I., Past-Pres. C.I. ; Dr. J. S. Owens, F.R.G.S., F.G.S., A.M.Inst.C.E.. 
Vice-Pres. C.I. ; Mr. C. H. Colson,' O.B.E., M.Inst.C.E., Past Member of Council 
CI. ; and Captain P. L. Marks, M.J.I., Licentiate R.I.B.A., Sec. C.I. ; and 
a numerous comjxmy of nicmliers, including Major J. Ernest Franck, F.R.I.B.A., 
Vicc-Pres. C.I. ; Sir y\lexander Gibb, K.B.l-:., C.B., and other guests. 



55 



THE CONCRETE INSTITUTE. [CONCCETEI 

In proposing tlie first toast, the President said : " I have the honour to pro- 
pose the health of the King, The King of the British J-lmj^re, the King of the 
British Commonwealth of Nations." 

In proposing the second toast, the President said : " Gentlemen, I have 
the honour to propose the toast of the Queen and the Royal Family, including 
the Prince of Wales, that bright young man, who is the reinforcement of our 
concrete empire." (Cheers.) 

Sir Charles Ruthen, O.B.E., in proposing the toast of H.M. Forces, said : 
" We have been so used always to a wonderful Navy, that we sometimes forget 
that these silent monsters are floating round, guarding this dear old island of ours. 
With regard to the Army, it is almost impossible to speak. At one time the 
British Empire had a tiny army, but the great citizen army, which was created 
during the War, was the greatest army which the world has ever known." • 

Lieut. -Col. H. S. Rogers, C.M.G., D.S.O., M.C.I., on rising to respond, 
said : " The proposer of the toast has dealt with the Navy. Unfortunately 
I did not know much about what the Navy was doing at the time, but I know now 
what it did. I know that we should not be here to-night were it not for the 
Navy. I myself spent most of the four years or more in the battle zones in France. 
I dare say that some remarks with regard to what I came across, relating to 
concrete, may be of some interest to members. Undoubtedly the Boche used a 
great deal more concrete than we did ; he was in a concrete country and could 
impress his labour. I recall one reinforced concrete bridge, which I had to repair, 
west of Cambrai ; it was a two-span bridge, carrying the main Cambrai-Solesmes 
road over two double lines of rail just north of the Cambrai annexe railway 
station. The rail was in a deep cutting with about 20 ft. from rail level to road 
level. The road on the bridge was paved with heavy setts with a narrow over- 
hanging footway on either side. The roadway was carried on a reinforced con- 
crete deck. At the time we took Cambrai, I was in charge of the bridges, the 
water supplies and the roads behind the actual fighting divisions ; the divisions 
fought in front, and we got shelled behind (laughter), because all our work was 
actually where the Boche had blown up things, and we had to make them good. 
On the morning of October 9th, 1918, we took Cambrai." (Applause.) 

Mr. J. W. Simpson, P.R.I.B.A., in proposing the toast of the Concrete Insti- 
tute said : "I am honoured by being invited here to-night and in having the 
privilege of proposing this toast of the Concrete Institute ' Con cresco ' — ' I 
grow together,' ' Concretus ' — ' United in growth ' ; I think the name is a most 
singularly happy one. Those of you who are not members of this Institute will 
learn with some surprise, I think, that it is only twelve years of age, with a present 
membership of 1,1 11. The Institute over which I have the honour to preside 
was founded in 1834, that is, eighty-six years ago. If the Concrete Institute 
continues to multiply in the same ratio as it has in the twelve years of its 
existence, I can see that by the time it has run its eight^'-six years it will 
embrace the whole population of the British Isles. (Laughter.) The histor\' 
of the Institute, though short, is very striking. It was at once recognised 
as worthy of standing beside the Institution of Civil Engineers, the Royal Insti- 
tute of British Architects and the Surveyors' Institution. We of the Royal 
Institute are rather proud of the position which has been achieved by our mem- 
bers in connection with your body, such as your present President (who is an 

36 



n 



roN5TBucnoNAJ THE CONCRETE INSTITUTE. 



Hon. Associate of the Royal Institute), Mr. Searles-Wood, one of your Past- 
Presidents, and an old friend and colleague of mine on the Council ol my Institute, 
Sir Henry' Tanner, another of your Past -Presidents, Mr. William Dunn, Major 
Ernest Franck, one of your Vice-Presidents, and many others. 

I cannot give this toast without some reference to the work of your President. 
He has accomplished an immense work. A great deal of it, as you know, is anony- 
mous, and I must respect his modesty with regard to that, but there is one work 
which he has done, and of which all of us know and speak, that is his work in 
connection with the Report of this Institute on the Standard Mathematical Nota- 
tion for Engineering Formulae. (Applause.) Its common sense and its practical 
utility have led to its acceptance to the exclusion of all other proposals. It is 
accepted and adopted in all Government pubhcations and official documents. 
It is one of the great educational works of modern times. It has saved time 
and energy in calculation, and it has cleared the pathway of the student. Such a 
work has not only enhanced your President's own already briUiant reputation but 
it is an honour and a glory to this Institute. (Applause.) I congratulate him and 
the Concrete Institute on that very great performance. Gentlemen, I ask you 
to drink with full glasses to the success and prosperity of the Concrete Institute." 

(Loud applause.) . . 

The toast was drunk with much enthusiasm, the guests rismg and smgmg 

" For he's a jolly good fellow." 

The Peesident, on rising to reply, was received with prolonged cheer- 
ing. 

He said :— " Gentlemen, I thank you very sincerely for the manner m which 
you have received this toast. I am prepared to discuss steel work, reinforced 
concrete and special methods of construction, but as you know, I resolutely dechne 
to be drawn into any discussion on politics or policy. Therefore I shall take great 
care to restrict my remarks to events in some other country or some other conti- 
nent, or some other century or epoch. (Applause and laughter.) For example, I 
absolutely decline to sav a word about the present shortage of houses or the dear- 
ness of clothing. (Laughter.) Instead of that I will tell you about the shortage 
of houses in Lagado about 234 3'ears ago. (Renewed laughter.) I quote from Dean 
Swift's account : ' In the year 1686, or thereabouts, certain persons went up to 
Laputa, either upon business or diversion, and after five months' continuance 
came back with a very httle smattering in mathematics, but fuU of volatile spirits 
acquired in that airy region. These persons, upon their return, began to dislike 
the management of everything below, and fell into schemes of putting all arts, 
sciences, and mechanics upon a new footing. To this end they procured a Royal 
Patent for erecting an academy in Lagado, and the humour prevailed so strongly 
among the people that there is not a town of any consequence in the kingdom 
without such an academ>-. In these colleges the professors contrived new rules 
and methods of building and new instruments and tools for all trades and manu- 
factures whereby they undertake one man shall do the work of ten, a palace may 
be built in a week, of material so durable as to last for ever.' (Laughter.) That 
sounds like concrete, but it is what Dean Swift says, and he goes on, ' The 
only inconvenience is that none of these projects are yet brought to perfection, 
and in the meantime the whole country lies miserably waste, the houses are in 
ruins, and the people are without food or clothes.' 



37 



THE CONCRETE INSTITUTE. [CQNCBETH 

There is another matter I sliould Hke to bring to your notice. The Ministry 
of Health Housing Department recently published a Standard Specification for 
Cottages. I refer to document SOP — 547/D82/7916. This is an excellent docu- 
ment in its way, but it contains no penalty clause, and having regard to the present 
tendency to use methods of construction having an uncertain standard of stability, 
and having regard to the tendency to reduce the standard of stability to the 
narrowest limits, I would suggest that the Ministry fall back upon precedent and 
incorporate some special clauses from the Code of Hammurabi, who was King of 
Babylon about 2,000 years B.C. He promulgated the first Building Act of which 
we have any definite knowledge, and he is supposed to have given a few hints to 
Moses himself. (Laughter.) The Code of Hammurabi states that ' H a builder 
has built a house for a man and his work is not strong, and if the house he has 
built falls in and kills the householder that builder shall be slaijt. If the child of 
the householder be killed the child of that builder shall be slain. If the slave of 
the householder be killed he shall give slave for slave to the householder. If goods 
have been destroyed he shall replace all that have been destroyed, and because 
the house that he built was not made strong and it has fallen in, he shall restore 
the fallen house out of his own personal properly. If a builder has built a house 
for a man, and his work is not done properly, and a wall shifts, then that builder 
shall make that wall good wilh his own money.' Those clauses tend to safer 
building. Gentlemen, time presses, therefore I will say no more, but I thank you 
for the way in which you have received the toast of the Concrete Institute, and 
for the kind references you have made to myself." (Applause.) 

Mr. F. E. Wentworth-Sheilds, O.B.E., Past-President C.I., proposed the 
toast of the Visitors. He said : " We are exceedingly pleased and proud to-night 
to see so many honourable guests facing us, so many Presidents of the various 
organisations bearing honourable names. The War has taught us many things, 
and among others it has taught us the value of co-operation. Our Societies exist 
ior co-operation of brains. I hope with confidence that in the future a great deal 
more of that co-operative work will be done between the various Societies who are 
represented at these tables. Among our distinguished guests are representatives 
of the various kinds of professions and of all schools of thought. It would be 
invidious to mention any of them in particular, but I have been asked to couple 
this toast with the name of one who, although not a builder, takes a very keen 
interest in building. Canon Alexander has a very soft spot in his heart for archi- 
tects, because he takes such an immense interest in that very fine w^ork, the 
restoration of St. Paul's Cathedral." (Applause.) 

Canon Alexander said : — " I have always felt ver}- great sympath}- with 
the case of Mr. Joseph Chamberlain, who was to make a great public speech on 
political subjects at a Midland dinner, when he was in the height of his fame, and 
the Chairman, at the proper time looking round upon his guests, turned to him 
and said, ' Mr. Chamberlain, shall we have your speech now, or shall we let them 
enjoy themselves a little longer ? ' (Laughter.) I feel sure that you have kindly 
invited me here to-night because of the very serious piece of work now being 
carried out upon the fabric of St. Paul's Cathedral. We have been occupied for 
the last eight years in trying to keep the Dome standing, and the end of that work 
is not yet in sight. I am afraid that we may take some twenty years to finish 
it, though we might perhaps do it in half the time if the funds at our disposal 

38 



f 3,cr>NyrBucrioNAiJ THE CONCRETE INSTITUTE. 

were larger. In the eight years that have passed, I have made one very strange 
discovery, and that is, that engineers and architects do not always take exactly 
the same view. (Laughter.) But though we have had a little ripple of difference 
on the surface, it has never interfered with the actual work, and we have gone 
forward and completed, I think I may say, the most vital portion of the unique 
piece of work executed upon that great building since it was first erected. There 
is an idea abroad at the moment that some Government office might possibly 
come into control, or partial control, of our cathedrals and our great parish 
churches. I venture to think, and I speak with the experience of one who has 
been Canon of two cathedrals for nearly twenty years, that there is no real necessity 
for that assistance. (Hear, hear.) Whatever may have been the case in the last 
century, it is certain that the Cathedral Chapters everywhere and the directors 
of our great parish churches are thoroughly alive to their responsibilities as 
custodians and guardians of the fabrics with which they are connected ; and 
moreover we are taking steps just now to open in every diocese in the land, 
committees who may see that the necessary work is carried out. I thank you 
very much on behalf of myself and the other visitors for the kind way m which 
you have received this toast." (Applause.) 
The proceedings then terminated. 



SPECIAL APPLICATION OF REINFORCED CONCRETE 

IN DOCKS. 

WITH SPECL\L REFERENCE TO THE REINFORCED 
CONCRETE GATES AT TILBURY DOCKS. 

By H. J. DEANE, B.E., M.Inst.C.E. 

The following is an abstract from a Paper read at the Ninety-Eighth Ordinuru 
General Meeting of the Concrete Institute on December \m, 1920. 

The paper was ilhistrated hy lantern slides and was followed by disciission.—i-AK 

The application of reinforced concrete to dock works necessarily includes many uses 
which are common also in other commercial spheres, for instance, sheds, warehouses, 
offices, railwavs, roads, jetties, bridges, etc. As such it is not proposed to include them 
in the subject matter of this paper except where any special considerations give them 
characteristics which have essentially to do witli docks and which arc only, or 
principally, associated tlierewith. 

Dock and River Quay Walls.— Among the worst conditions with which the engineer 
is frequently faced arc those in which tlie geological formation consists of unstable 
strata sucli as are found in many of the estuaries in Great Britain and elsewhere. In 
the Thames vallev. for instance, the conditions arc far less favourable than those where 
solid rock or clialk foundations can be obtained without much difficulty and at no great 
deptli and where the superimposed strata are of a much firmer character. 

Tlie strata immediately underlying tlie northern bank below London Bridge 
consist mainly of alhivium and river drift which have been deposited in the cour.se ot 
aires by tlic river itself. 

'l-hc-nlluvium, however, in wliich the Victoria and Albert and Tilbury Docks sy.stcm 
are for the most part constructed is of a nature (particularh- ni the latter case wlicro 
diffirulties arc constantlv being met, and although the original cock walls at lilbury 
were constructed in open trench, yet when the Tilbury Main Dock Extension was 

39 



REINFORCED CONCRETE IN DOCKS. [(jQNCRETE] 

first commenced the alluvium (or what is locally known as " bungum ") had become 
so soft, probably owing to its being saturated with water from the docks, that it was 
found impossible to proceed in open trench and the walls had to be carried down 
to gravel by sinking a series of monoliths side by side on the line of the quay 
walls. These monc liths were built up of pre-cast concrete blocks, each layer 
breaking joint with the one below, and were designed so that four pockets or wells 
were left from which the material at the bottom could be grabbed out. As the 
material was removed so the monolith sank and more layers were built up. There 
was no reinforcement in the blocks, which weighed up to 5 tons each, the size of the 
monoliths being approximately 30 ft. by 30 ft. 

At Valparaiso reinforced concrete monoliths were used in forming the Customs 
Quay Wall, and somewhat similar monoliths were used at Copenhagen and sunk in 
position as caissons. 

A number of examples are to be found where L-shaped walls have been adopted 
for river and quay work with the necessary stiffening brackets or gussets to support 
the vertical portion against both external and internal pressure. 

A notable example of an L-shaped wall is to be found in Sydney Harbour, where 
pre-cast trestles were sunk into position on a prepared rubble bed and the space behind 
filled up and reclaimed. Tlie total length of wall was about 1,350 ft. and it served as 
a retaining wall and quay wall combined, the total height of each trestle being 
21 ft. 6 in. with a 15 ft. horizontal leg and having a width of 3 ft. 6 in. 

Reference might here be made to the quays immediately behind the quay walls 
at Tilbury Docks. The original designs did not take into account the extraordinary 
nature of the ground, as no experience had been obtained of its want of stability. 
The quays were simply surfaced with ordinary concrete. The heavy traffic and the 
yielding ground underneath have, however, produced a state of things which now and 
then necessitates pulling up the old concrete, filling up the spaces due to settlement, 
and then re-concreting ; but the underlying material never becomes properly solidi- 
fied, and for any further extensions the question of constructing such quays in reinforced 
concrete with suitable sirpports will have to receive careful thought. Indeed the 
whole design from the quay edge right back to the sheds may have to be radically 
altered . 

Lock Entrances and Graving Docks. — These two facilities form essential features 
of most dock undertakings, the provision of lock entrances being determined by the 
consideration as to whether the range of tide is large enough to necessitate the conser- 
vation of the water in the docks. There would appear to be very considerable scope 
here for adopting reinforced concrete caissons which could be erected in situ and sub- 
sequently sunk to the correct level, or possibly by dredging out a AN-ide trench the cais- 
sons could be floated into position and sunk, the slope behind being subsequently 
filled in. 

Floating Dry Docks. — These have man}' advantages over the ordinary graving 
dock, more particularly where local circumstances make the construction of the latter 
difficult and costly. Such docks are generally built of steel or iron. It is obvious in 
any case that the maintenance of such structures adds enormously to the cost of 
working, and the advantages from the use of reinforced concrete have been recognised 
and one (if not more) of such docks has been constructed and is now in use. 

Slipways. — Whilst on the subject of ship repairs reference should be made to the 
use of slipways. Timber, steel and iron have been used extensively for the ways, but 
owing to the heavy loads imposed and the rapid deterioration of such materials between 
wind and water reinforced concrete has been successfully used. 

In America launching (or slip) ways 990 feet long built in reinforced concrete 
were erected in connection with the construction of some new warships about three 
years ago, and in the same country a group of ten ways 270 feet long were constructed 
for the repair of river patrol vessels on the Missouri. 

Lighthouses and Beacons. — Numerous examples of the successful use of reinforced 
concrete in lighthouse works can be found, and little comment is necessary-. The main 
point to be borne in mind, however, as in all work exposed to attrition and the action 
of salt water, is sound impervious concrete with ample covering to the steel reinforce- 
ment. 

40 



r . coNyrpuc-noNAH REINFORCED CONCRETE IN DOCKS. 



Groynes and Sea Defences.— Reinforced concrete has been extensively used in 
such works more especially in Holland, where some very ingenious mter-locking 
devices have been adopted for the purpose of preventing erosion to the banks of dykes 

and river walls. , • , ,■ , . 

The design overcomes the disadvantages connected with continuous structures 
bv providing pre-cast flat slabs i8 in. square by 2I in. thick and placingthem chess- 
board fashion: the white squares having lips or projections under the black square, 
which in turn are kept down in place by concrete pegs. ^. ^ r ■ . , 

Pontoons and Dummies.— Without encroaching on the subject of reinforced 
concrete ships and barges reference must be made to the employment of this material 

for pontoons and dummies. ,.,•,, .u -ri a 

Many instances of the former were to be found in the docks on the Thames and 
a considerable number of such pontoons were in use at one time. These ^'ere gener- 
ally built of steel or iron, but in due course they became worn out and obsolete and 
at onetime it was proposed to replace them with reinforced concrete pontoons. The 
designs provided ample strength against crushing, and the heavy timber endenng 
formed an important feature, but owing to the gradual abandonment of the use of 
such craft no further steps have been taken m this direction. 

The dummies employed in the floating landing stages m connection with steam- 
boat Diers and in the larger types such as those at Liverpool and Birkenhead offer 
splendid opportunities ior construction m reinforced concrete The consideration 
of dead weight does not materially affect the question and, as they can be very fully 
protected by suitable fendering or belting, damage by coUision is a remote contingency^ 
Crane Tracks and Underground Conduits.-The large growth in the size of sh ps 
and the increase in the weight of loads to be handled, whether on the quay side or for 
repairs purposes in dry dock, have produced a corresponding increase in the dimen- 
sions and lifting capacity of cranes and other hoisting appliances. In the early days 
when hydraulic cranes were first introduced their capacity rarely exceeded 2 tons or 
their total weight 20 tons. To-day ordinary quay-side cranes have a lifting capacity 
of from 3 to 5 tons and for the dry dock side may be anything from 15 to 20 tons up- 
wards The wheel loads are consequently ver>' great and special construction has 
to be provided for their support. Considerable lengths of such tracks have recen ly 
been laid by the Port of London Authority. They are supported on pre-cast pi es 
driven down till a good foundation is secured. These are spanned longitudinally 
by pre-cast girders supporting the crane rails with pre-cast ties to prevent the tracks 
from spreadfng. The ties are generally placed below the bottom of the longitudmal 
gkdlrs so as to allow of the construction of concrete conduits for the trolley wires 
or feeders which supply current to the electric motors. The conduits are s rengthened 
at ntervals with pre cast reinforced concrete yokes somewhat similar to the cast-iron 
yoies used in tramway construction. Ver>^ little trouble has been experienced from 
narrowing of the slots and, generally speaking, the arrangement has proved very 

'^'''a number of 7 ft. gauge cranes are also provided in the vicinity of the Authority's 
dry docks and these are nearly all laid on pre-cast sleepers, designed by the author 
the great drawback to them, however, during construction, is their weight and the 
liability to damage in transit. , . 

Before passing to the last subject of this paper the author would like to refer in 
some detail to an unusual application of the use of reinforced concrete m connection 
wiSi the old lock entrance It the Victoria Docks on the Thames. These docks and 
the lock entrance were built as long ago as 1855 and were designed on ^^ ^conomical 
a scale as possible, although considerable foresight was exerosed ^" P^^^^^l^^^f /^. ^^^^^ 
of such large dimensions as 80 ft. between copings and 28 ft. of water belo^^ Tnni > 
Hig Water mark. The gates, which are of iron, are constructed with a double skm 
and the whole of the 95 tons dead weight is carried on the pintles and ro lers .^le^i 1 e 
buoyancy chambers are flooded. The rollers are supported on cast-iron segme is 
secured t^:. the bottom of the lock. The constant use of the gates -on^X^^:^\ v.^il.i^^. 
inability of the cast-iron segments to withstand the l'^^^y/^«"^^"|'^^*"^j;^,^f "l^^t 
resulted in the seating under the segments becoming damaged to ^'''\f''^^'^l''^^^^^^^ 
some radical method of reconstruction of the roller paths has become aboluteh neces- 

41 



REINFORCED CONCRETE IN DOCKS. ICQNCPFT^^ 



sary. It was hoped tliat by the time this paper was written the reconstruction would 
have been completed, but circumstances have prevented this, and tiie effectiveness 
of the design has not, therefore, yet been put to practical test. 'Jhe reconstruction 
referred to is to be carried out by removing the old paths and bearers and forming a 
chase (to be cut out by diver) capable of taking a pre-cast curved girder having a radius 
of about 39 ft. and a cross section of 36 in. by 22 J in. and provided with a suitable 
recess for the reception of the cast steel roller path segments. Steel bolts are cast in 
position for securing the segments in correct alignment and eyes or lugs are provided 
for lifting the girder from the quay side and depositing it in its correct position in the 
lock bottom. The levelling up will be effected in the usual way and the spaces between 
the old lock structure and the girder will be filled in with cement grout. The girders 
are designed for the worst conditions during lowering and fixing, and special arrange- 
ments are to be made so that when suspended all the slings will take their fair share 
of the weight. 

Reinforced Concrete Lock Gates at Tilbury Docks.^ — The exigencies of the war 
necessitated the introduction of reinforced ccjncrete in the construction of ships, barges 
and other vessels, owing to shortage of the more usual materials such as steel, iron 
and wood. 

The bviilding of a certain number of such barges on Admiralty behalf was under- 
taken by the firm of Chris iani and Nielsen and a suitable site was let to them for this 
purpose by the Port of London Authority at their docks at Tilbury, Essex. The 
great advantage of this site was the ready access to the river, and the low marsh level 
on which the barges could be built obviated the formation of expensive slipways 
or dry docks. All that was necessary to enable the barges to be floated out into the 
Tilbury Dock was a cut or passage of sufficient width and depth through the pitched 
bank. 

The closing of this passage against the waters of the dock was the subject of 
careful consideration, and the contractors eventually decided, with the permission of 
the Port Authority, to build the necessary lock gates of reinforced concrete. '■ 

The entrance passage or channel from the Dock Extension is 40 feet wide in the 
clear. 

The level of the top of the sill at the entrance is 3-13 ft. above Ordnance Datum. 
The level of water in Tilbury Docks at Spring tides is approximately Trinity High 
Water or 12-5 ft. above Ordnance Datum, so that at this level there is a depth of water 
of 9-37 ft. in the entrance to the barge dock. The level of top of coping is 17 ft. above 
Ordnance, the distance from coping to sill being 13-87 ft. 

The sill is segmental in plan, the radius being 26 ft. 4I in. 

The curved outer faces of the gates are flush with the outer face of the sill and 
the leaves of the gates are 13 ft. 8 in. deep from top to bottom, there being a space of 
2 in. between the bottom of the gates and the top of the sill. 

Each leaf consists of a slab 3I in. thick with double horizontal and vertical rein- 
forcement of I in. rods spaced 6 in. apart, and is stiffened by four horizontal ribs for 
the whole length, and one vertical rib at the centre of the leaf is introduced between 
the horizontals. 

The top horizontal rib is widened out to 2 ft. to form a gangway over the 
lock and has a treble system of reinforcement of I in. rods with ^ in. stirrups at 4 in. 
centres. In thickness it tapers from 5I in. to 3^ in. and is haunched at the connection 
with the slab. The two horizontal ribs are 12 in. by 5 in. doubly reinforced with 
J in. rods and J in. stirrups, 6 in. pitch. The bottom rib is 12 in. wide and tapers 
from 6| in. to 5 in. in width. The vertical centre rib is 10 in. by 5 in. with double 
reinforcement of | in. rods, I in. stirrups, 6 in. pitch. 

Heel Post. — The heel post is 12 in. by 12 in. exclusive of haunches and is 
reinforced with four | in. rods and four i in. rods from top to bottom. 

The horizontal lacings are generally | in. diameter at 6 in. pitch, but at the top 
and bottom they are placed 4 in. centres and additional } in. rods are introduced. 

The reinforcing bars of the horizontal ribs and the slab are carried into the heel 
post, the ends being hooked round the verticals. 

On the top and bottom there are | in. steel plates, 12 in. square, and the vertical 
I in. rods are screwed into these. 

42 • 



/vlNy^^STN'otg REINFORCED CONCRETE IN DOCKS. 



The centre line of the heel post coincides with the centre line of the 3 J in. slab. 

Bottom Pintle. — An additional J in. metal plate is fixed on the bottom by four 

I in. countersunk screws and there is an elongated hole 4I in. by 5^ in. in each plate 

to allow of the heel post tightening in the hollow quoin under pressure of the 

water. 

The bottom pivot consists of a steel pin 4 in. diameter held in position by a 
built-up girder of two channels with top and bottom flange plates and built into the 
concrete. 

Top Pintle. — The top pintle is a 4 in. diameter steel rod fitted into a gaspipe 
ferrule in the concrete. The anchorage consists of a 9 in. channel secured to the 
concrete by holding-down bolts with anchor rods. There is an elongated hole 5J in. 
long in the channel to allow of adjustment. The anchor strap passes round the top 
of the pintle and through a cast-iron lug fixed to the channel, and can be adjusted 
by a nut in the shore end, sufficient play being allowed for the automatic tightening 
of the gates when subjected to the pressure of water. 

Quoins. — Water-tightness is secured by a timber quoin fixed to the concrete post. 
This is 12 in. wide and the face is curved to a radius of 12 in. The hollow quoin is 
not curved in the usual manner, but is tangential to the timber face. The timber is 
fixed to the concrete b}^ | in. diameter screws fitting into tapped sockets built into the 
gate about 12 in. pitch reeled. 

Mitre Posts. — The mitre posts are 12 in. by 5 in. haunched to the slab and rein- 
forced with six vertical rods -| in. diameter with horizontal stirrups \ in. diameter, 
spaced 6 in. pitch. 

The meeting timbers are out of 10 in. by 4 in. fastened to the reinforced concrete 
by- 1 in. screws in tapped socket similarly to the heel post. The timber projects 
beyond the outer edge of the meeting post and is bolted to a 5 in. b}^ 3^ in. vertical 
timber attached in the concrete. The width of the meeting face is 6 in. and the centre 
line coincides with the centre of the 3^ in. slab of the gate. 

There is no clapping sill in the ordinary sense, but watertightness at the bottom 
of the gate is secured by means of two leather flaps bolted to the reinforced concrete 
through the top edge with ^ in. bolts and over-lapping the sill of the gate recess about 
5 in. The pressure of water forces these into close contact with a timber facing strip 
attached to the concrete sill and the gates are quite watertight. The inner of the two 
flaps (about | in. thick) is acting at low heads of water when the force is not sufficient 
to move the thicker flap (about f in.). At higher pressure the latter is, however, 
forced tight against the sill and is capable of standing the full 14 ft. head of water. 
Should the thin flap for some reason or other give way, the thick flap will act as an 
emergency tightener and close up by the rush of water. 

At the heel post where the flap would foul the sill when the gate is opened a loose 
piece of leather is fixed and is pulled up out of danger by a rod operated from the 
gang-way. 

The gates are opened and closed by horizontal poles fixed on supports at the heel 
post and at the centre of the leaf similar to those used on canal gates. To ensure cor- 
rect mitreing, stops are fixed on the abutments so that the leaves cannot be closed 
too far, and a hinged locking plate is attaclied to one leaf engaging with vertical bars 
built in the other. 

Two lifting eyes are cast in each leaf to facilitate unshipping in case of necessity. 
The dry dock is filled through sluices in the gates. These are 12 in. square and 
one is fitted in each leaf towards the mitre post and about I ft. above the sill. 
The concrete is stiffened round tlie sluice with \ in. diameter rods, the verticals 
being carried to the ribs above and below. The paddle and guides are of timber and 
the edge of the concrete round tlie openings is faced with | in. steel plate flanged 
to fit. The valves are operated by means of a hand wheel from the gangway, the top 
ends of the rods being supported in a reinforced concrete post. 

The gates were erected in position, a temporary dam of carlh being left on the 
main dock side until after testing, which was carried out bv water introduced between 
the temporary dam, tlie test head being i ft. above Trinity Higii Water. 

The drawings were prepared by Messrs. Clnisliani and Nielsen and approved by 
the Chief Engineer of the Port of London Authority after the necessary amendments 

43 



REINFORCED CONCRETE IN DOCKS. [CONCBETE] 

to the original designs had been made. These consisted mainly in the introduction 
of horizontal and vertical ribs and modifications to the top and bottom bearings. 

These gates were not designed for frequent operation, and were only used when 
it was necessary to float out the concrete barges which were constructed inside the 
dry dock. 

DISCUSSION. 

The President, in opening the discussion, said that until one saw the slides and heard Mr. Deane's 
lecture one hardly realised the extent to which reinforced concrete had crept into use in dock work. 
Indeed, it seemed that we could not do without it, and in years to come its use would spread more and 
move. 

Mr. F. E. Wentworth-Sheilds, O.B.E., M.Inst.C.E., in proposing a hearty vote of thanks to Mr. 
Deane for 'his paper, said he supposed that (;nc of the things we had to thank the war for was that 
it really did make us rack our brains to find new uses for reinforced concrete. We were able to get 
a certain amount of steel, as well as gravel and a little cement, but not very much, and at the same 
time we found it almost impossible to get steel sections and timber, even at the prices which 
were charged for these luxuries, so we set to work and did what we could with our concrete materials 
and our round bars, and Mr. Deane had shown that we had managed to make some practical things 
out of this combination. He was very interested in the large hollow monoliths, referred to in the 
early part of the paper, and also the referen es to the monoliths used at Tilbury. Although he 
himself had not had the opportunity of making reinforced concrete monolith's he had several times 
looked into the question, and he was inclined to agree with the author that, on account of the 
trouble and expense involved, for a structure like a gravity wall, whether hollow or solid, the 
cheapest way in ordinary circumstances was to build it of plain concrete in the form of blocks or 
in the form of a mass. But when they had to build a wall in deep water, which meant that they 
had to carry their materials out into deep water somehow, and especially where the foundations were 
of doubtful material, it was quite likelv, it seemed to him, that the reinforced concrete caisson would 
rival other designs, because it was possible to make that caisson on shore and then float it out to its 
final position, and therefore avoid the use of expensive stages or cranes to handle the enormous weights. 
In that wav they could get very large caissons or large sections of wall into their final positions with the 
least possible trouble and expense. On that account there was no doubt that in such a case reinforced 
concrete was a very serious rival to the old-fashioned solid wall construction. In respect to reinforced 
•concrete groynes, he had alwavs understood that one trouble with them was that they were liable to 
fret away by the travelling shingle on the beach. With regard to bollards, he was very interested to 
see these made with reinforced concrete, and there was a good deal in what the author had said with 
regard to the superiority of the old-fashioned cast-iron bollard. They would probably be interested 
to know that the bollard which his firm had designed for the White Star Dock at Southampton, where 
some of the largest ships in the world were constaiitly docking, consisted of a hollow cast-iron casing 
containing what might be called reinforced concrete, i.e., it was filled up with concrete reinforced with 
nickel steel sections, railway rails as a matter of fact, and the great strength of that bollard was prin- 
cipally due to the reinforced concrete. It was designed to stand a horizontal pull of 50 tons, as it was 
estimated that such a pull might be exercised by a ship of the dimensions of those used to-day, and 
the only way to satisfactorily make bollards strong enough to resist that pull was by filling the hollow 
iron casing with reinforced concrete. 

Mr. H. K. G. Bamber,J.P.,F.C.S., etc., said he had detected a tone of sadness in the author's remarks 
when d'escribi'ng'the methods of construction which might be adopted when there was not enough 
cement to be got. That sadness was also echoed in Mr. Wentworth-Sheilds' remarks, and perhaps it 
would be a grain of comfort to Mr. Deane and other engineers and contractors to know that those who 
govern the destinies of the cement industry were hopeful, if not hampered by Government interference, 
that during next year they will have completely got over the terrible dislocation of industry caused 
by the war, and would be able, not only to reach their pre-war output of cement, but considerably exceed 
it. Therefore, if that was possible, Mr. Deane and others would not have to worry themselves about 
getting out special designs of constructon in which to make docks if an ample supply of cement were 
not obtainable. 

Mr. A. T. Walmisley, M.Inst.C.E., said that Mr. Deane had the advantage of a sheltered position, 
as he had "said that the reinforced concrete gates were not used every day. He had adopted a very 
good form in the wall being circular to equalise the pressure on the level. With regard to concrete 
groynes, he personally was not in favour of them generally speaking. They were built, perhaps, at 
an angle of i in 10, and sometimes required either lowering or raising to suit the accumulation of beach, 
and this could be done much more easily when t ey were constructed of timber. 

Mr. C. S. M9ik, M.Inst.C.E., said that the most interesting point in the paper to him was the ques- 
tion of dock gates. He had never seen any reason why a dock gate should not be made of reinforced 
concrete, and why the fittings, not onlv the heel post but the cill and the way the gate fitted up against 
the cill, should not be the same as in the case of a steel gate. He took it that the leather flap to which 
the author had referred was merely a temporary arrangement, because he understood the gate was 
only constructed to satisfy a temporarv need. He did not see why the gate should not be made like 
a steel gate, but the weight had to be taken into consideration. 1 he weight of a wooden gate was very 
much less, and with steel gates the weight was almost taken up by the flotation of the gate in many 
cases, and that was the reason why steel gates had been so universally adopted for large entrances. 
In the gate shown on the screen there was no roller ; the gate was simply supported on the pintle and 
hung from the anchor posts. That principle should be adopted in all gates. He had always put a 
roller under them, the reason being not that the weight came on the roller when the gate was in — 
it should come on the pintle and on the anchor posts — but in case the gate became water-logged. Tn 
that case, however, the remedy created the disease, because the man in charge of the rollers never knew 

44 



U cr>N5TPuc-naNAn REINFORCED CONCRETE IN DOCKS. 

[Ci. FJNOIT^I^ PING — 'J 

f^r i^„„^H . thp hpct nart of the weight was on the roller paths when it should 
h''\'eelCtl"\nchor Pofts^^'T^^^^^^ the old Vietoria iSock entrance, which 

have been on ^'^^ ,^^,*^^'°'^ P°^p "s ^f ^eing put right, but it was going to be a most expensive process. 
Avas now, apparently, ii^^processot being pmr^gi g altogether. He had found a great 

i" f"?'drL\dUMn'crneSi^on wi f ^e wlr"^^^^^^ path due to' the surface of the roller path 

i^^ li.n^H so\hat X ac ion of the sea water commenced as soon as the path was submerged. If 
being planed so that ^^e aciiou o ^gj^ained intact and the roller paths lasted very much longer, 

the cast iron was not planed the surfac^erema^^^^^ wooden v. reinforced concrete 

With regard to Mr. WenUv^r^^^^^^^^^^ ^^.^^ ^ ^^^^, ^^^^^. , ^, .Single, 

groynes. On the soutn coasi v^aere giu> - considerable amount of erosion. 1 his 

and whether they put dow^^concrete ^^^^ ^.^^ ^.^^^^ ^^^ gravel and sand 

also apphed *« P^^^^. f.\ Pl^'^f^lfes if^^^^ in the case of reinforced concrete, once the skin breaks 

wears it ^^Jj^/ ^^f^ "^ ™ ^^ntVe a^i^d th4 pile is done. The only thing to do in these cases was 
away the sea water gets to the s^eei an P ^^ ^^^^ ^^^ ^^^^^^t^ verv much stronger 

to put a very much Heavier coveiingovci dorks said the author had mentioned ihat the 

cent, per annum of the '^^^P tai 7=;' ";' i^_„^ .r t^g Amsterdam Dry Dock Company, in which it was 
for repairs ; it was m perfectly good condition and vn as expe^^^^^^ to la another point in regard 

that would .,»t rust ,vas also ^/X^P^'f '■ ^f/^"' gJ'^JlS artved a? might be of interest to the 

-rai:uSd°eMi^r^»nl;^^^^^^ 

i„ a steel dock. There was a point !•= "7" l''',\ » ("^.'."i""? 'S have had a depth of .0 ft., and 
JLItinWedli.Jg' iUer'^^rltfoTi-er '.o mat the%r,o1ced concrete do?, possible, which 
necessarily increased the cost. 

THE LECTXTRER'S REPLY. 

to deal with. He agreed that the P^oP^r thmg to do^vas to n^^^^^^^ ^^ ^^ ^^^^^ ^^.^^P ^ ^^ 

and there was a great deal more to be done m the direction otnnaig ^^^ ^^^^^^ ^^ 

had had some experience with sewers i" London .In ^he case ^^ °J^^ '^^^^4 1^^^ f^^^^d that the bricks 
which was originally made of Stafford hire ^^^^^^ to the strength of neat 

had been worn away and fhe cemf^nt was let standing up r^^^ ^^^^ ^^^^^^^ ^^ ^^. ^^^ 

cement. He was very interested '^^Jjie bollard at bo^^^^^ ^.^ ^^^^ ^^^ ^^^p^ 

Wentworth-Sheilds, and he was of the opinion that thejmigntiaKe a controversies as to 

something of the same character, ^^^th regard to do^^^^^^ He had kno^^•n cases where 

whether it was desirable to have the g^^^e^ supported on rom;re or nm „ ^-^^^^ t^e rollers 

gates were supposed to hav-e been ^.^PPo^^ed on rolk^ b^^^he^thev had gone or whether they would 
could not be found, and no trace had been d seoyered as to ^^nere t ey g ^^^ ^^^ ^^^^^^ ^^^^ 




into being, and vvhen there was a very greai pressure oi»m^^^^^^^^^ « ^ ^^^_^^^^ ^^^_ 

ments put in hand as soon as possible, and consequentlv th^^^ to abandon the use of rollers 

sideration which would have been "ecessary before dmd^^^^ ^^ ^^^^^^^ ^j^^ ^,^^^^„^^ 

under the gates. In the new sclreme for ^h^ ^mprojemen^ o^^^e m ^^^^^^, ^^^^ ^.^^^age is 

lock is loo ft. wide and the depth 45 ft., ^'^.^ ^^^f^^f^^'^^^iX . certain amount of mud in the gates. 

f,ffK„l.;,v.»h'?tt^s^L-%t7ii'^^r|:«^^^^ 

when Mr. H. Kempton Dyson would read a Pf.f^ on Tests «" "'f t^^^^'^'^'J^^ in establishing 

been for many years the Secretary of the Institute, ?^dM,f°"^^^„|^^t-n recommit ion of the work he 
the Institute, and he trusted that the "^^f b^^rs.,^"^/;;^^^^^^ the Institute would 

f^oi^rfo? tlJl^l^e of^^m^ln^i^TrT.^^^^^^^^ -- ^-"^ *« -"' 



about 



45 



A REINFORCED CONCRETE W II ARE. 



[CTSCBEfE] 




Fig. I. General View of Wharf. 



A REINFORCED CONCRETE WHARF FOR MESSRS. CRAIG, 
TAYLOR & CO., LIMITED, AT STOCKTON-ON-TEES, 

By A. C. MESTON, Licentiate, R.I.B.A., M.C.I. 

A STRUCTURE presenting several interesting problems has recently been com- 
pleted at Stockton-on-Tees in the shape of a wharf for Messrs. Craig, Taylor & Co., 
Ltd. The length of the wharf frontage to the river is 408 ft., and the overall 
width of the deck is about 12 ft. A railway track had to be provided for to 
enable cranes to be moved to any part of the wharf for purposes of loading and 
unloading the vessels lying alongside. The weight of these cranes together 
with the load they are capable of lifting is approximately 40 tons each. 

The wharf is built upon reinforced concrete piles. The piles along the front 
of the wharf are 16 in. by 12 in. in section and 29 ft. long, and are driven at 8 ft. 
centres. The piles along the inner side of the wharf are of similar section but 
34 ft. long. The length of these piles was necessitated by the nature of the 
ground. Two trial piles of timber which were driven before the concrete piles 
were cast did not obtain the required set until they reached about 16 ft. below 
the dredged level of the bottom of the river. The back row of piles was driven 
at 16 ft. centres. The wharf is tied back at 16 ft. intervals to " dead man " 
piles, which were driven 30 ft. from the inner' face of the wharf. These piles 
were 18 in. by 18 in. in section and 15 ft. long. Immediately behind the front 
row of piles, and extending right along the wharf, reinforced concrete sheeting 
piles 18 in. by 7 in. in section and 21 ft. long were driven. After driving, the 
top 2 ft. or thereabouts of the main piles was cut out exposing the steel, and the 
reinforced concrete columns carrying the decking of the wharf were carried up 
from these. 

The tops of the sheeting piles were also cut away about 12 in. and the exposed 
steel was incorporated with the beam running along the front of the w^harf at 



r o. CXaM5TKUCTlOTMAL| 
IK EMGlMy-F.P 1 NO — -J 



A REINFORCED CONCRETE WHARF. 



the top of the main piles. The sheeting piles are designed as propped cantilevers, 
the reaction at the top of these piles being taken by the horizontal beam at the 
lower end of the sloping slabs. The reactions from these beams are in their turn 
taken up by the i6 in. by 8 in. sloping beams shown on the drawing, which are 
tied back by the land-ties to the " dead man " piles. 

The general arrangement of tying back the wharf by land-ties had to be 
somewhat altered at one portion of the wharf, owing to the proximity of an exist- 
ing building. This will be seen on reference to the plan, Fig. 2, and the general 
arrangement of ties provided in this portion is indicated clearly on the plan. 




PLAN OF WHARF 

Fig. 2. 




GROUND L 


r v I 














fe SLAB 




LAND T'l - 












' ;i 



^* jyc[-p ff'-i- 



K.[g MAIN PILL 



Kl.T SMLLT PILL^ 



Fig. 3. 

CROSS SECTION OF 
WHARF 




V 



v" 



Though it was impossible to drive piles inside the existing building it was found 
possible to carry one of the ties underneath the floor of this building. 

Holes were cast in the columns and beams along the front of the wharf to 
allow for bolting the timber fenders and rubbing pieces to the concrete work. 

The whole of the work was on the Kahn system, designed by the Trussed 
Concrete Steel Co., Ltd., of 22, Cranley Gardens, South Kensington, S.W. ; the 
contractor who carried out the work was Mr. H. M. Nowell, of Stockton. 



47 



RULES FOR CONCRETE ROAD CONSTRUCTION 





SIMPLE RULES FOR 
CONCRETE ROAD 



CONSTRUCTION. 



!^?1, I 



Since Portland Cement has been manufactured and used in commercial quantities 
in connection with construction work, the cement itself, the aggregate, and the 
result of the concrete have been the subjects of careful study through thousands 
of tests by engineers and chemists throughout the entire civilised world. Whole 
volumes have been written as to types of cement, sand, aggregate, the amount 
of water, and, in fact, all phases of concrete work, but too frequently this 
information is studied by engineers only, and the man who is actually doing the 
work on the job is left in at least partial ignorance as to the best methods of 
making concrete and the reasons why other methods will not secure as good 
results. 

Now, however, that concrete roads are being adopted to a much wider 
extent than hitherto it is essential that all who are engaged in the work should 
be in possession of such information as will enable them to carry out the opera- 
tions in an intelligent and efficient manner, and that they should be impressed 
with the importance of neglecting no single means for the production of good 
concrete and a sound structure. 

Concrete roads to be economically possible must be laid in comparatively 
thin slabs of 6 in. to 8 in. 

In addition to the properties required of concrete in ordinary building con- 
struction, concrete roads must withstand great impacts, must resist the abrasive 
action of traffic, and must be able to withstand wide temperature variations, the 
direct action of frosts and rains, and to do this without undue wear or cracking. 

This means that any defects, no matter how small, in concrete roads are very 
quickly made evident by their failure, and failures in concrete roads, unless 
immediately repaired, start to wear in what would otherwise be perfect parts 
of the road. 

With due regard to conditions encountered in actual practice and to the 
necessity for adapting ideals to practical materials and methods, the following 
simple rules, if carefully observed, have been found to give perfect concrete roads 
without materially increasing their initial cost. 

SUB- GRADE. 

Be sure that the sub-grade on which the concrete road is to be laid is thor- 
oughly compacted and that an ample drainage system is provided. 

MATERIALS. 

Use only clean, sharp sand and clean gravel or hard crushed stone. There 
are certain other materials which can be used for large aggregate, but the 

48 



.■EMGTNEEKING 



^ RULES FOR CONCRETE ROAD CONSTRUCTION. 



availability and relative cheapness of gravel or crushed stone make them the 
ideal aggregate for most jobs. The initial cost of clean materials is only very 
slightly greater than the cost of unwashed and ungraded materials. 

THE PROPER MIX, 

Depending upon the type of road and the amount of traffic, work out the 
proportion to be used. Having once determined the proper mix, make 
arrangements so that this proportion will be rigidly adhered to in each batch. 
Numerous ways of automatically measuring cement, sand, stone and water 
are now on the market, or if these are not available, home-made devices can 
be substituted and equally good results secured. In general, concrete for 
roads should be of the proportions one part cement to two parts of sand to four 
parts of stone, and especial care should be taken to see that to these ingredients 
is added only a sufficient amount of water thoroughly to dampen the entire 
surface of each particle of the mix ; any surplus water is an actual detriment to 
the strength of the concrete. 

THE NECESSITY OF THOROUGH MIXING. 

Be absolutely certain that each batch is thoroughly mixed and is uniform 
throughout. The best results can be secured most cheaply and economically by 
utilizing one or other of the numerous types of batch mixers, since the use of such 
mixers does away with the possibility of error, which is a necessary part of all 
manual work. However, the best of concrete can be secured by hand mixing 
provided someone constantly supervises the mixing and sees to it that the mass is 
cut over and over and over until the sand, stone, cement and water are thoroughly 
incorporated. 

DEPOSITING AND CONSOLIDATING THE CONCRETE. 

As soon as the mixing is complete the concrete should be deposited in approxi- 
mately its final position as rapidly as possible, and immediately following this it 
should be thoroughly consolidated. The transportation of the concrete from the 
mixer or mixing board to its final position can be done in various ways, perhaps 
the quickest and most economical method being the use of a chute, or trolley and 
bucket, such as are attached to a great many of the concrete mixers which have 
been especially built for road construction. The use of one of these mechanical 
devices does away with the delays which usually follow on a dependence on men 
with wheelbarrows. 

In consolidating concrete, by far the best results are secured by the use of 
mechanical tam])ing and finishing machines which automatically screen, tamp 
and finish the concrete in a very short space of time. It has been found that the 
use of these machines gives a road which is of uniform strength throughout and 
does away with the weak spots, which are almost inevitable when this is done by 
men with tamj)ing tools or rollers. As in mixing, just as good results can be 
secured by manual labour but at a very much greater cost and only under constant 
supervision. The objects of the requirement for speed in depositing and con- 
soHdating the concrete are two-fold. Getting the concrete into final position and 
tlioroughly compacted with all possil)le rapidity means taking full advantage of 
the entire strength of the cement. This is not the case where ;in a}-)prcciable 

49 



RULES FOR CONCRETE ROAD CONSTRUCTION. [CQNCBEn^ 



length of time elapses between the start of the mixing and the Inial hnish off. 
The consolidation of the concrete is all important in eliminating v(jids caused by 
such air as may be encased in the concrete and by surplus water which may also 
be encased in the concrete. Rapid tamping or punning tends to eliminate these 
voids and to give a dense mass. 

GENERALLY. 

After the concrete is in position, consolidated and finished, great care must 
be taken that it is not disturbed and that it is kept covered with some damp 
covering until it is finally set. 

The cost of careful observance of these points means only a few pence per 
yard added to the initial cost of concrete roads ; failure to observe them or any one 
of them may and probably will mean a road which will disintegrate under traffic 
within a very short time. On the other hand, it has been thoroughly demon- 
strated that careful observance of these principles will result in a roadway which 
will withstand ordinary traffic for a long period of years with a minimum cost for 
maintenance, and that throughout its entire life a concrete road will present a 
smooth, even surface for traffic. 

MEMORANDUM. 

Concrete Tanks Hold Light Flash Oil. — During nearly tw o years' test, three concrete 

tanks at the Traftord City foundry of the Westinghouse Electric and Manufacturing 
Company, U.S.A., have proved satisfactory as fuel oil containers. Recently one of 
the tanks was used to store transformer oil, and held the light flash oil as easily as the 
heavy fuel oil. 

Each of the tanks has a dia. of 37 ft., with a capacity of 125,000 gals. Built of 
reinforced concrete, the tanks have successfully resisted the weather, and the little 
seepage that occurred was easily stopped. A recent inspection of these tanks was 
made by a representative of the United States Bureau of Standards, in making a study 
of the use of concrete tanks for storing oil. 

These containers, which were built from specifications based on information 
received from engineers from the Portland Cement Association, have been used to store 
oil for use both in the foundr}- and works at East Pittsburgh, Pa. 




Reinforced Concrete Tanks for Storing Tr.\nsformer and Fuel Oil. 
50 



j^ CX)N5TeUCTlC8VAU 
. ti. ENGTNEJJilNG — il 



CONCRETE FLAX RETTERY IN BELGIUM. 




CONCRETE FLAX 

RETTERY IN 

BELGIUM 



By WILLIAM WREN HAY, Assoc. Mem. Am. Soc. C.E. 
We reproduce below an interesting description by Mr. WiUiam Wren Huij, 
Assoc. Mem. Am. Soc. C.E., published in "Concrete, U.S.A." — Ei'. 



A VERY interesting example of an unusual use of concrete is found in the hot-water 
retteries constructed in Belgium, along the River Lys. The retting, or steeping. 
of flax is a very important industry in the neighbourhood of the Franco-Belgian 
frontier, especially around Courtrai. The large amounts of straw sent here from 
France and from the contiguous districts resulted in the construction of several 
artificial retteries,* which hasten the decomposition by the action of hot water 
and enable a much larger quantity of straw to be treated and at the same time 
extend the season. The choice of concrete was inevitable for these plants, as 
the cost of erection must be a minimum and at the same time the nature of 
the work requires first-class construction. The arrangement usually consists 
of a series of retting vats with hot and cold water tanks above them. Cold water 
is pumped into the topmost tank, whence it flows by gravity through a boiler, 
is heated to about 95° F., and flows into a lower tank or reservoir, from which it 



Cjoef! - » 







Flax Rettkry ni:ar Courirai, Bi;lch;m. 

is drawn off to the vats below. The vats containing the straw arc filled from 
piping laid along the floor, the water rising through the straw and overflowing 
at the top. Originally the plants were quite conventional in their arrangement,- 

♦ LcgiaiKl \'aii SteoiiUisto Patents. 

51 



I 



CONCRETE FLAX RETTERY IX BELGIUM. [(jQNCREJD 



having separate elevated steel tanks for hot and cold water, the vats being large 
pools into which wooden crates containing the straw were plunged by travelling 
needle carriers. These plants proved too expensive in operation, and the overhead 
charges ate up all profits, as the competition from the usual hand labour along the 
river, limited the revenue that could be collected. Recognising the possibilities of 
cheaper construction, these entirely concrete plants were developed, and are 
now to be seen at several places. The operations are so far simplified through 
the arrangement of tanks and vats in vertical series in the same structiire that 
two labourers and an engineer or fireman can handle more than 300 tons per 
season of 8 months. Inspection of several of these plants which have been 
in use five years or more showed no leakage in general, and several were quite 
dry inside, in spite of the overflow at one end. When it is considered that during 
fall weather the outside temperature may be below freezing and the water is 
kept at nearly 100° F., it is a tribute to the builders and to the materials used. 
The water of the Lys is practically free from lime, hence its popularity among 
flax growers. No other care was taken to waterproof these plants other than 
the usual minute care observed throughout Europe in placing concrete. The 
vats shown in the sketch have a volume of about 50 cubic metres each, and will 
hold five tons of straw, being filled four or five tifnes each month. The tanks 
have a like capacity, or about 15,000 gals. each. The plant shown cost about 
5p3,ooo before the war, and has a capacity for retting 500 tons of straw per year. 



MEMORANDA. 

Seven Subjects we should Know more About. — The American Concrete Institute 
have selected seven subjects for special study and consideration at the next convention 
of the Institute in February, 1921. 

(i) Standardisation of the contractor's plant for reinforced concrete building 
construction ; (2) the best possible treatment of structural concrete so as to give attrac- 
tive results in colour and texture. Contractors are giving more attention than they 
used to in America to the surface finish of their work ; (3) the housing problem and 
the use of concrete in aiding its solution ; (4) standardisation of units of design of 
reinforced concrete building construction ; (5) floor finish ; (6) roads ; (7) the great 
increase in the cost of timber necessitates a reconsideration of the question of form- 
work. Steel forms leave something to be desired from the point of view of economy, 
and their successful use might depend a great deal upon more careful study, and this 
work will also be in the hands of a special committee dealing with the question of the 
standardisation of units of design. Nevertheless the reinforced concrete contractor 
gives more attention than he used to to steel forms. 

Concrete Jor Large Apartment Houses in Washington.— A large apartment house is 
being erected in Washington of reinforced concrete, faced with brick and limestone. 
It is being erected in two sections, one section being completed, the work having been 
carried out in less than seven months. The entire building will contain 1,000 rooms, 
making 350 apartments of various sizes. The architect is Mr. Philip M. Jullien, 
Washington, D.C. All concrete is spouted through steel chutes, supplemented by 
short wood sections. Floors are of concrete joists and hollow tile. Stairways are 
poured complete with stringers, risers and treads, at the same time as the floor just 
below. An architectural feature of the buildings is the placing of concrete balconies 
along the inner courts of every floor. — From Concrete, U.S.A. 

32 



[&g;?i^g^N^'^J HANDBOOK FOR CEMEXT AXD CONCRETE USERS. 




POPULAR HANDBOOK 
FOR CEMENT AND 
CONCRETE USERS.* 

Second Edition.) 



A Review. 

Although the uses of cement and concrete have expanded enormously during the jast 
decade or so, and have extended to farm and estate, home and garden, road and railway, 
town and country, the literature on this subject has not grown in the same proportion, 
and it has been felt that there v,-as still a place for a semi-popular book of general type 
that would prove interesting and, without being too technical, useful, that would bring 
home to the mind the great economic and artistic qualities of concrete as a building 
material and help in producing a higher grade of concrete work. These are the criteria 
stated by the authors in the preface, which have influenced them in the production of 
the present volume. We welcome this work, therefore, which meets a definite want, 
and since theoretical methods which have more of an academical interest than a 
practical value have been omitted, it is essentialh^ a book for the non-technical reader. 

The instructions and suggestions in these pages are based upon American practice 
which, in some directions, is far in advance of our own, and the book, which rightly 
emphasises the importance of the concrete being of the first quality, is a valuable 
contribution to the literature of the subject. 

The book is divided into six sections and contains thirty-three chapters. 

Chapter I is introductorj', and serves to show to what extent concrete has entered 
into our lives. An extract from a speech by the late Mr. Andrew Carnegie, one of the 
greatest authorities on the production of steel, is worth quoting : " Fortunately the use 
of concrete, simple and reinforced, is already reducing the consumption of structural 
steel. The materials for cement and concrete abound in every part of the country^ ; 
and while the arts of making and using them are still in their infancy, the products 
promise to become superior to steel and stone in strength, durability and convenience and 
economy in use." [The italics are our own. — Ed.] 

The utilitarian qualities of concrete have long been known and more or less fully 
appreciated, but its ajsthetic possibilities are only beginning to be realised in our own 
country. In this connection the present book claims, what has for years been advo- 
cated in the pages of Concrete axd Construction.\l Engineering, the dawn of a 
new style of architecture ; a style entirely free from the hereditary tendencies of the 
ancient and medijcval styles, and Avhich could be rendered possible only by the intro- 
duction of a new material, possessing properties entirelv distinct from those whose 
possibilities had been studied and studied for ages. The essential features of the new 
style are pointed out in Chapters IX and X. 

Reference is made to the valuable work done in the United States by means of the 
bulletins issued by the American Association of Portland Cement Manufacturers, b}'^ 
means of which a wide dissemination of the knowledge of tlie possibilities of cement has 
been effected. Work in our own country is being carried out on similar lines by the 
Concrete Utilities Bureau of London. 

* Myron H. Lewis.C.E., and. Mbert H. Chandler, C.H. HoddcrandStoughton, priooi? shillings net. 
F 5i 



HANDBOOK FOR CEMENT AND CONCRETE USERS. [CDNGBETE] 

Chapter II deals with the different hmes and cements, dividing tlie latter into 
Portland cements, Natural cements and Puzzolan or slag cements. 

The crystallisation and colloidal theories are touched upon but briefly since, while 
of opinion that the question is of great importance to the cement manufacturers, the 
authors admit that the subject of cement setting is yet in a controversial stage. 

The methods of manufacture of the three kinds of cement occupy about four 
pages, but special mention is made of White Portland Cement and the materials with 
which it is mixed to produce white concrete for use in a large variety of specified ways, 
almost entirely ornamental. 

Stress is laid upon the importance of storing cement in a dry place ; if, through the 
absorption of moisture either from the ground or from the atmosphere it becomes lumpy 
or even a solid mass, it is useless and should be thrown away. * 

In Chapter III the properties and requirements of hydraulic cements are set forth, 
and the methods that may be employed by the cement user in order to determine 
whether the material is up to the standard and fit for use are described. 

\\'hat may be regarded as the subject matter proper of the book commences with 
Chapter IV — Concrete and its properties. 

So much is heard nowadays about the addition of compounds for increasing the 
strength and densit}' of concrete that it is interesting to note the conclusions at which 
the authors have arrived. They say " An ideal concrete is a mixture with a minimum 
percentage of voids. This result is obtained by grading the aggregate and mixing in 
such proportions that the voids in the coarsest aggregate are filled by a finer aggregate, 
the voids in which are, in turn, filled by a still finer aggregate, the cement itself being so 
finely ground that its granules will completely coat those of the finest aggregate, ^^'hen 
this condition obtains, the set will produce a mass of everlasting stone." 

The function of the water is carefully explained, the general conclusion arrived at 
being that " The effect of different proportions of water upon the ultimate strength 
depends chiefly upon the density of the resulting mortar ; the consistency which 
produces with a given weight of the same materials the smallest volume, after setting, 
of Portland cement paste or mortar gives the highest strength. Dr>--mixed mortars 
usually test higher than wet after short periods, as they set and harden more rapidly, 
but more uniform results in practice can be attained with plastic mixtures. 

The aggregates — sand, broken stone and gravel — are dealt with in Chapter ^' and 
the question of the necessity for " sharp " sand discussed. 

The importance of the cleanliness of the aggregate is emphasised in this chapter 
and simple methods of washing are indicated. 

The danger of using natural mixtures of gravel and sand is pointed out, and it is 
proved that the extra labour required to screen and re-mix the material is more than 
compensated for by the saving in cement. 

Proportioning is discussed in Chapter VI. In this chapter the instructions with 
regard to water do not appear to agree with those suggested by the results of the 
researches carried out by Mr. Duff A. Abrahams. We agree that " The principal thing 
to bear in mind in order to obtain the densest possible mixture is to eliminate the voids 
in the concrete mass," but the statement that " plenty of water to obtain a wet mix 
should be employed, as water will drive out the air entrained between the particles of 
the aggregates " may be true as far as it goes, but any excess of water beyond that 
required for the chemical changes necessary to the setting of the cement and hardening 
of the concrete will, when dried out, leave voids. As a matter of fact this is admitted 
in the same chapter. 

"Mix rich and mix wet to obtain the best work " we consider a distinctly dan- 
gerous doctrine. 

* Under " Cement Notes " in this issue, tfie advantage of storing cement in bulk, rather than in 
sacks, is discussed. — Ed. 

54 



[&i^.S^iNGS HANDBOOK FOR CEMENT AND CONCRETE USERS. 

Included in this cliapter is a simple and practical method for determining the 
proportion of voids in the aggregate. 

Chapter VII. The right note is struck in the opening sentence of this chapter : 
" The proper mixing and placing of concrete is fully as important as is the proportioning 
of its ingredients." Within certain limits, our experience is that it may be even more 
important. 

The instructions for mixing the sand and cement are quite sound, but we do not 
like the method advocated for adding the coarse material and the water when hand 
mixing is employed. By this method the coarse material is placed on the top of the 
levelled sand and cement mixture, but is not turned over while dry. The instructions 
continue : — " Add about three-fourths the required amount of water, using a bucket 
and dashing the water over the top of the pile as evenly as possible." It is claimed that 
by this method an extra shovelling is saved. It seems to us, however, that a better 
result will be obtained by turning over the whole of the mixture dry, and then adding 
the measured quantity of water, slowly, through a rose, while the materials are being 
further mixed. 

Useful illustrations of home-made tools for the concrete worker are to be found in 
this chapter and the advantages of the batch mixer over the continuous type are duly 
set forth. 

A method of obtaining an even, homogeneous face to concrete work which is often 
neglected is that of " spading " the wet material next the " form." This is dealt with 
in detail. 

Concreting in freezing weather is touched upon very briefly and the employment of 
common salt for lowering the point at which water will freeze is mentioned. This, 
however, we do not advocate, because in severe weather it defeats the object at which it 
aims, since the salt has the effect of retarding the setting of the concrete, a result which 
it is important to avoid. We consider the only safe methods to be those of heating 
the sand, stone and mixing water, or covering and housing the work while in progress. 

Chapter VHI deals with " forms " for concrete construction, most of which are in 
conformity with ordinary American practice. This includes a formula recommended 
by Sanford E. Thompson for designing forms. 

Chapter IX on the architectural and artistic possibilities of concrete, though 
consisting of some three pages or so only, contains many passages worth quoting, e.g., 
" True art is always the result of a clear and forceful expression of the idea and use of 
the structure." 

Then, after discussing the temptation to imitate stone or other construction in 
concrete, " The future of concrete treated architecturally lies in a development on 
surfaces and not lines." 

Many more extracts might be given from this chapter, but space forbids. 

Chapter X deals with concrete residences. This term has a much wider meaning 
in the United States than in our own country. In the States, the concrete " residence " 
includes every variety of house from the cottage to the palace. In this country it is, 
with a few notable exceptions, entirely confined to the cottage. 

In Chapter XII various methods for the artistic treatment of concrete surfaces are 
described, and include, amongst others, rough-cast, pebble-dashing, exposure of the 
aggregate by scrubbing, etching with acid, tooling, tinting, panelling, mosaics and 
carving. 

Tliis aspect of concrete work has been but little regarded in this country, but those 
to whom the aesthetic side of constructional work appeals will find that by the adoption 
of one or the otiier of the methods de.scribed, concrete possesses vast possibilities for 
artistic treatment which are quite legitimate and which enable it to express its own 
individuality. 

Concrete blocks and their manufacture form tlic subject of Chapter XI 11, and we 

F 2 55 



HANDBOOK FOR CEMENT AND CONCRETE USERS. {CCNCY^£^E1 



agree with the writers that concrete blocks should not be used in a building until they 
are from thirty to sixty days old. 

The artistic side of concrete is continued in Chapter XIV, which describes the 
making of ornamental products, the methods being divided into two general classes, 
modelling and moulding. This chapter contains much useful information on a little 
known side of concrete practice. 

Chapter XV deals with the manufacture of concrete pipes and fence-posts. In tlie 
latter the method of attaching the wire fencing principally adopted in this country, 
viz., by perforations in the post, is not mentioned in the text. 

Section IV, containing Chapters XVI-XXI V, is devoted to the Principle of Design 
and Construction in Reinforced Concrete, and the explanation of the theory, together 
with the various tables and formula-, will be found of great practical interest to engineers 
and others responsible for the design of important works. The other subjects included 
in this section are Systems of Reinforcement, Reinforced Concrete in Factory and 
General Building Construction, Concrete in Foundation \\'ork. Retaining Walls, 
Abutments and Bulkheads, with a table of earth pressures, and Arches and Bridges. 

Chapters XXV-XXIX, which constitute Section V, describe the uses of concrete 
for special purposes and include Sewerage and Drainage Works, Tanks, Dams and 
Reservoirs, Sidewalks, Kerbs and Roads, Concrete in Railroad Construction, and the 
utility of concrete on the farm. With reference to concrete roads and footpaths stress 
is rightly laid on the importance of a well-consolidated foundation, but the suggestion 
that the concrete road may be put into service at the end of a week if the weather 
conditions have been favourable is not in accordance with modern practice. 

As might be expected, a large number of ways in which concrete can be employed 
on the railway are set forth, but American engineers still appear to be in pursuit of the 
ideal type of " tie " or " sleeper " which will be perfectly efficient under all conditions 
of traffic. One suggestion put forward in this book, viz., solid concrete road beds for 
special locations on railways, is well worth consideration. 

As on the railway, so on the farm, there is practically no limit to the variety of 
uses to which concrete may be applied. The most important of these are described in 
detail in Chapter XXIX and a list of others given. 

The last section of the book, comprising Chapters XXX-XXXIII, is entitled, 
" Important Miscellaneous Data on Concrete Construction," the subject of the first 
of these Chapters being " The Water-proofing of Concrete Structures." So much has 
been written in this Journal on the question of water- proofing that little need be said 
here. W^e do not agree that, as a general statement, the " striking fault of concrete is 
its great thirst for water." Of course it is a scientific fact that every substance is more 
or less porous, but by using a good cement, and with proper care in the selection and 
cleanliness of the aggregate, in proportioning, mixing, handling and curing, such a high 
degree of impermeability can be secured as to render the material to all intents and 
purposes watertight. 

Grout, or " liquid concrete," and its uses are dealt with very fully in Chapter 
XXXI ; and the importance of inspection, and the work of the Inspector, together with 
a summa-ry of the essential rules and principles for securing good concrete work are 
treated exhaustively in Chapter XXXII. 

The last chapter of the book is devoted to the cost of concrete work, but as the 
figures do not apply to this country at present prices, comment is not necessary. 



56 



rTxoNSTBUcni 



lONAU 



CONCRETE IN THEORY AND PRACTICE. 



CONCRETE IN THEORY 
AND PRACTICE. 

^ete rS<iTe interested in (he subject on Us educah ve side. 

REINFORCED CONCRETE SIMPLY EXPLAINED. 

By OSCAR FABER, O.B.E., D.Sc, etc. 

Tn this series of articles it is proposed to keep explanations so simple as to be 

■ , 11^ hi^innl^mne desirinn to understand the underlying principles of reinforced 

intelligible !^.^y'^'^.^^^^^^^ „ m of mathematics. The results will be accurate 

concrete iri;/iottmdi«p^/iro«a^«o^/ ^ .^^ ^^ ^^^^ ^^ ^^^erstand. The 

ZticZ\hZ7£o iina:T::Uent introduction to those u-ho .ill need to folio, 
them up with a more advanced work.—i^v. 



CHAPTER IV. — continued. 

Shear Resistance of Concrete Beams. 

66. Examples of the rules already given 
will now be worked out in detail. 

Fig. II (a) shows a T beam i6 ft. span 
carrying a central point load of lo^. 

The centre moment is 

WL^io^xi^^xia^ 3^ tons inches. 

4 4 

The area of steel required at mid span 

A _ -;;; = ^"S sq. inches. 

6-f" diam. rods give 6 x •6 = 3-6. 
If we dispose the bars as in Ftg. 11 {a), 
the shear resistance will be the same at 
every section. 

The shear is 5 tons = 11,200 lb. 
The shear resistance at any section 
will be the vertical component of the 
inclined rods, added to the vertical com- 
ponent of the inclined compression in the 
concrete. This latter, in a symmetrical 
design like the one given, may be taken 
equal to that of the inchned rods. 

Now the force in the inclined bars is 
Area x stress 
1-2" X 16,000 = 19,200 lb. 
The vertical component is therefore 
be 
JO, 200 X — 
^' ac 

= 19,200 X — „ = 6,600. 
54 
Similarly, vertical component _ 6,600 
of inclined compression ""13,200 

In this case stirrups are therefore not 
necessary. Nevertheless, for several 
reasons, a few are desirable, and we may 
therefore adopt the minimum, say | in. 
diameter, spaced apart a distance equal 
to the depth of the beam, say 24 in. 

Note in passing — 



(i) These inclined compression forces 
can only exist when the bottom rods 
are excellently secured at their ends. 

(2) These inclined tension forces can 
only exist when the inclined rods are 
excellently secured at their ends. 

(3) The stirrup at the support is par- 
ticularly effective in preventing the hooks 
from unbending. 

(4) The forces can be worked out 
graphically or otherwise by treating the 
beam as a lattice girder. 

67. Suppose now we consider a beam, 
of same span and size as before, but with 
a distributed load of 20 tons. 

The moment at midspan will be the 
same as in the last example, and there- 
fore the same steel will be required. 

The shear, however, will now be 10 
tons at the end, varying uniformly to 
zero at midspan, and therefore a different 
arrangement of rods will be required, 
giving a greater shear resistance at the 
end and a less resistance near midspan. 

Such an arrangement is shown in Fig. 
II (6), where the rods at the end are bent 
up steeply, the next system less steeply, 
and the centre part having no bent-up 
rods at all. 

In a case like this, it is desirable to 
calculate the shear and the shear resis- 
tance in each of the panels ab, be, and cd. 
End panel ab. 

Shear = I o'T =22,400 lb. 

Shear by inclined bars 

area x stress x -r 

20 
1-2 xi6,ooox -g =13.700 

Shear by inclined compression = 13,700 



Total shear resistance 
This is therefore satisfactory. 



= 27,400 



57 



CONCRETE IN THEORY AND PRACTICE. 



[CONCRETEJ 



POINT iipUD OF 



6 ~ 3^=3 



Jf' 




^S ■ % POOS ^ 2 ■ Y KODS 

e'- o" 



2- i ROOS 



(a) 



^B STilSRjPS 



5£:CTI0N MlDSPGN 



LJ 



U-^^ 



20 TONS uNiroRM ^oao i /b'sLis 



V//////////^///////z///}///y////////y//////////'//////////y/////////////''j''////////////^ 




F,o (J?) 



58 



a, CON.STBUCTIONALI 
A ENGlNEEJilNG ~^1 



CONCRETE IN THEORY AND PRACTICE. 



Second panel be. 

Shear at &=| xio'^ =16,800 lb. 
Shear resistance by inchned bars 



=area x stress x- 



= 1-2 X 16,000 X 



40 



= 9,600 



Shear by inchned compression =9,600 



19,200 



This is therefore satisfactory. 
Centye panel cd. 

Shear at c =f x lo'^ =8,400. 
If we rely on diagonal tension, we have 
safe shear resistance 

=60 X depth X width 
= 60 X 20" X 10" 
= 12,000 lb. 
This is therefore satisfactory. 

Note. — (i) Both the last examples are 
what are called b}^ the author " double " 
systems, in which any vertical plane is 
cut by an inclined tension and an inclined 
compression. For many reasons, such 
systems are to be preferred. 

(2) The inclined compression must be 
stressed to over 600 Ib./sq. inch. For 
this purpose, the breadth of the band 
may be taken at one-quarter the total 
depth. 

Now the force in eb is 1-2 x 16,000 

= 19,200 lb. 
The area of the band is 
width X breadth 
10" X 6" =60 sq. in. 
The actual stress is therefore 



19,200 
6o~ 



= 320 Ib./in.^ 



which is satisfactory. 

The inclined compressions in Fig. 1 1 
(a) and {b) are called " indirect " by the 
author, as they do not carry the load 
direct to the support (as in Fig. 10 {e) or 
(/), but act only in conjunction with the 
shear reinforcement. 

68. It will be interesting to .see how 



much shear the beam would have carried 
by direct inclined impression if no shear 
reinforcement of any kind had been used, 
and all the bars carried along to the end, 
as in Fig. 11 (c). 

Using the rule in par. 65 of 500 lb. per 
sq. inch, multiplied by the ratio of effec- 
tive depth divided by the span, we have 
end shear due to direct inclined com- 
pression 

■ 1 •, depth 
= 500 X depth X width x ■ 



= 500 X 20 



X 10 



span 

20" 

192" 



X- 



= 10,400 lb. 

In other words, this beam, without 
shear reinforcement, would have carried 
a uniform load of 20,800 lb., or nearly 
10 tons. 

For this purpose, the percentage of 
steel must not be less than -675. In our 
beam it is 

3-6 X 100 

-^ =1-8, 

20 X 10 

more than is required from this con- 
sideration. 

Note that if, as a rough check, we take 
the parabolic arch as 6 in. wide, the safe 
force in it would be 

600 X 10" X 6" =36,000 lb. 
The slope at the end is — „, or|, giving 

a shear resistance of 12,000 lb., agreeing 
fairly well with the 10,400 from our rule. 
As a general rule, it is undesirable to 
take full advantage of the existence of 
this shear strength without reinforcement 
because the parabolic arch in Fig. 11 (c) 
crosses the inclined compression forces in 
Fig. II [b) and therefore the concrete 
would be stressed twice. It will not be 
necessary here to consider the exact 
treatment of such cases. Nevertheless, 
this strength is often of. great importance. 



39 



CEMENT NOTES. 



ICQNCBETEJ 



CEMENT NOTES 

By Our Special Contributor. 



Loam and Clay in Concrete Aggregates. 

Specifications for concrete usually 
provide that the aggregate shall be free 
from loam and clay, but as there are vary- 
ing interpretations of what constitutes 
freedom from loam and clay, and as there 
are large quantities of concrete produced 
without the protection afforded by a 
specification, it will be of interest to 
consider what happens when certain 
aggregates are used in the state that 
nature presents them. 

The strength of concrete lies particu- 
larly in the adhesion of the cement to 
the aggregate, but if the latter is sur- 
rounded by a film of loam or clay which 
is not removed during the concrete 
mixing process, it is certain that although 
cement may adhere to the film, the 
adhesion of the latter to the aggregate 
is negligible so far as the strength of 
concrete is concerned, and thus the 
strength of the concrete is reduced. 

On breaking up concrete made from 
unwashed pit gravel, it is generally 
possible to remove, with ease, pebbles 
which have little adhesion to the mass, 
and on examination of the bed in which 
these pebbles have lain, a film of loam 
can frequently be detected. Such con- 
crete, when broken up by force, yields 
a large proportion of pebbles free from 
adherent mortar, while on the other 
hand, with a clean aggregate, the dis- 
integration of the concrete involves 
breakage of the pebbles. 

It will be obvious, then, that in the 
case just considered, of pebbles and sand 
coated with loam, the proportion of the 
latter necessary to affect seriously the 
strength of the concrete need only be 
trifling, probably 2 or 3 per cent, would 
suffice. But, take the case of an aggregate 
in which the loam or clay is not adherent 
to the sand and pebbles, but is in the 
form of mud disseminated throughout 
the aggregate and not coagulated. In 
such a case it is probable that the effect 
upon the strength of the concrete may 
be merely that caused by the greater 
surface to which the cement particles 
are called upon to adhere. There must 
■of course be a limit to the proportion of 
loam or clay that can be present without 
damage to the cement, but this hypo- 
Go 



thesis explains why it is possible in some 
cases to add clay to concrete without 
any harmful effect. 

From these preliminary considerations 
it can be understood that in practical 
experience a pit ballast containing as 
much as 20 per cent, of loam can some- 
times produce a good concrete, while 
another pit ballast, containing no more 
than 5 per cent, of loam and used under 
similar circumstances, may yield a very 
poor concrete. It is often difficult to 
convince a Clerk of Works that because 
he has used an obviously loamy ballast 
with success on one contract, he may 
not necessarily be able to use a less 
loamy material with an equal hope of 
success. 

What, then, should be the criterion 
when determining the suitability of 
sand or gravel for concrete ? Obviously 
the best test is the crushing strength 
of cubes composed of the material under 
examination with a cement of known 
quality. The usual test of shaking the 
aggregate with water in a graduated 
glass cylinder and observing the pro- 
portion of loam or claj- after settlement 
is also a useful one, and any material 
containing more than 10 per cent, of 
such impurities should be scheduled as 
requiring washing ; but this test does 
not reveal the aggregates with strongly 
adherent loam, which are so undesirable. 
Lumps of coagulated clay can usually 
be seen by examination with the eye, 
and such aggregate should be excluded 
unless the lumps can be removed by 
washing. 

A common effect of a loamy aggregate 
is to retard the hardening of the concrete, 
and this effect is generally more marked 
in a cold, damp atmosphere than under 
warm dry conditions. Such concrete is 
of course more liable to damage by frost 
than a quick-hardening concrete. 

It is a curious fact that some cements 
yield better results than others when 
used with loamy aggregates, and it is 
not uncommon for a contractor to find 
that two brands of cement (both comply- 
ing with the British Standard Specifica- 
tion) yield markedly different results 
with the same aggregate, one cement 
giving a satisfactory result as judged 



\l. CON.TCUCTIONA 
L^ ENG1>1E£R1NG 



1 



CEMENT NOTES. 



by the eye, and another producing a 
slow-hardening concrete which may in 
winter take several weeks to reach a 
reasonable strength. The cause of this 
•difference requires elucidation, but it 
appears that quick-setting and quick- 
hardening cements are less liable to the 
■deleterious effect of a loamy aggregate 
than slow-setting and slow-hardening 
cements. 

The Portland Cement of the Future. 

The issue of a new revision of the British 
Standard Specification for Portland 
Cement recalls the conditions of twenty 
years ago when cement manufacturers 
had a dozen or more specifications in 
their Specification Books and were pro- 
ducing half a dozen different varieties of 
cement to satisfy their customers' varied 
tastes. 

In those days, the cement salesmen 
bravely accepted any specification offered 
to them, and cement works executives 
strove to fulfil them. The test variously 
known as " immediate immersion," " cold 
plunge," or " sudden death " was one of 
the chief terrors, and when combined with 
a slow-setting specification required great 
ingenuity on the part of the tester before 
a satisfactory result could be displayed. 
The " bottle test " and " rise in tempera- 
ture test " were other items of specifi- 
cations at the beginning of this century 
which have now happily been abandoned. 

The British Standard Specification of 
to-da}^ is not ideal but it possesses the 
confidence of cement users and cement 
manufacturers, and at least serves the 
purpose of excluding weak and unsound 
material. It is hardly to be doubted, 
moreover, that any general improvement 
in the quality of the cement produced 
in this country will depend upon the 
alterations made from time to time in the 
Standard Specification, or in other words, 
tlie Portland Cement of the future will 
depend upon the Standard Specification. 

Improvement in tensile tests is an 
obvious development likely to occur, and 
from the fact that cements are already 
on the market witli higiier tensile tests 
at seven days, both neat and sand, than 
demanded by the Standard Specifica- 
tion, it is reasonalile to conclude tliat the 
specification of the future will .set liiglier 
limits. Cement of sucli strength sliould, of 
course, enable the constructional engineer 
to economise in tiie dimensioning or pro- 
portioning of his concrete. 



Another improvement which might 
well be standardised is the faculty of 
rapid hardening. Under present condi- 
tions, so long as cement develops a cer- 
tain strength at seven days, it is regarded 
as satisfactory, the rate of gaining strength 
during this period being ignored by speci- 
fications although of great importance 
to cement users. 

Slow hardening is a frequent complaint 
of concreters, and those who have inves- 
tigated the subject in the laboratory 
know that this behaviour of concrete 
is to some degree attributable to the 
cement, even though the latter may com- 
ply with the British Standard Specifi- 
cation. The neat tensile strength of 
commercial cements at 24 hours may varj'- 
from 150 lb. to 350 lb. per square inch 
and the hardness of concrete at the same 
age would vary accordingly. 

The value of a rapid hardening con- 
crete is self-evident and any improvement 
in this direction would be of great advan- 
tage to the cement user. A neat tensile 
strength of 400 lb. per square inch at 
24 hours is not unattainable, and it is 
possible that the Standard Specification 
of a decade hence may contain some 
such provision. 

Fineness of grinding is another property 
of cement which may be the subject of 
improvement in the future. Cements with 
residues of 3 per cent, on the 180 mesh 
sieve are already well known, and if 
better air-separating apparatus be devised 
for cement grinding there is no reason 
why even this fineness should not be 
improved upon. Finer grinding will of 
course tend to bring about the rapid 
hardening and the high strength at seven 
days already discussed, and it is conceiv- 
able that as fine grinding is practically 
no more than a means to an end, the 
Fngineering Standards Committee of 
ti)e future may be content to set the 
strength limits and leave the fineness 
and other means of obtaining the strength 
to the discretion of the cement manu- 
facturer. 

The soundness of cement is a ciuality 
in which no improvement seems to be 
necessary. The present standard — the 
Le Chatelier test^has proved by experi- 
ence to be an adequate protection against 
expansive cements and no good purpose 
would be served by reducing the limits 
of expansion now contained in the Stan- 
dard Specification. 

61 



NEW METHODS OF CONSTRUCTION . 



ICDNCBETEl 




NEW METHODS 

OF 
CONSTRUCTION 



T. \u^V:^M^^^;^^j^j 




In recent issues we have given a /is/ of new methods of construction which 
have been passed by the Ministry of Health in conneriion with housiny srhe>ne.«, and 
so that oui readers may have fuller particulars of these ?nethods, irr proposr publish- 
ing some further information regarding same, based on dctaih supplied to us 
by ttie different firms putting forward new methods. — Ed. 



THE HESSIAN FABRIC SYSTEM OF CONCRETE CONSTRUCTION. 

Under this method, which presents some novel features, the walls are erected 
in situ by means of wooden moulds which are raised course by course until the wall 
is complete. 

The speciality of the system and that which gives it its name is that when the 
shuttering is set for each course, before being filled with concrete the whole of the 
mould is lined with very coarse " Hessian " with sufficient left over at the sides to 
wrap over the top. Thus it will be seen that each course is entirely encased in the 
fabric, and that when the moulding boards are removed the fabric covers both the 
inner and outer faces of the wall. 

If the wall is to be plastered, rough-cast or rendered the fabric is left in position, 
in order to provide a better key for the added coat. 

It is stated that Hessian fabric does not rot when bedded in cement. 

To the moulding boards fillets are attached, in order to produce on the wall the 
appearance of bonding joints, and so to imitate stonework. If no external after-treat- 
ment is intended the Hessian is cut away with knife or scissors. 




Fig. 1. This Photograph shows the Scaffolding .Arrangement for supporting the Wooden Moulds. 
62 



»^ CON5TRUCTIONALI 
A ENGITMEEJJING — J 



NEW METHODS OF CONSTRUCTION. 




Fig. 2. Showing thl Mluiuij oi Hreciing a Solid Wall. The Hessian Fabric is seen, laid 

BETWEEN THE MOULDING BOARDS BEFORE THE CONCRETE IS FILLED IN. In THE FOREGROUND 

ARE THE Moulding Boards with Fillets attached. 






Fig. 3. 1 HIS shows a portion of the Interior of a Oarage built on this Svste.m. 
Fabric has been left on the Walls, which are ready for Plasterino. 



t\i 



NEW METHODS OF CONSTRUCTION. 



[CONCRETE] 



The real object of the fabric is to hold the concrete together when the moulds 
are removed, which is done immediately they are full and the fabric bedded down on 
the top. 

Cavity walls may also be built on this system. In this case cores are placed in 
the mould after the fabric has been placed in position, each two lengths of core being 
separated by a space. The concrete which fills these spaces forms a concrete wall-tie. 
The cores are removed before the outside boards are taken down. 

It is claimed that the fabric, by crossing the cavity, prevents the latter being filled 
up at the bottom with mortar as is often the case in building cavity walls. 

For ordinary cottages it is said that the whole of the work can be done from the 
inside of the building with the aid of a few trestles. 

In erecting a house, after the foundation is laid, pairs of wooden verticals are 
set up all round the site, one of each pair being on the outside and one on the inside 
of the wall. The verticals are perforated with holes at 12-inch centres. These holes 
which, in the case of each pair are in register, are for the accommodation of the bolts 
which hold in position' the moulding boards which lie on the inner sides of the uprights. 
The arrangement is seen in Fig. i. When the moulds are full the bolts are removed, 
the boards raised for the next course and the work resumed. 

The promoters claim that four labourers mixing concrete and one man and one 
boy building will complete a wall containing an equivalent of 3,000 bricks in a day of 
■eight hours. 

The system, the patentee of which is Mr. J. Clements of Northfleet, has been 
approved by the Ministry of Health, provided the Ministry's specification for concrete 
work is complied with. 

A NEW SYSTEM OF SHUTTERING. 

•One of the results of the increased cost of building has been the reduction to an abso- 
lute minimum in State-aided housing schemes of all artistic adornment and archi- 
tectural features which are designed solely to add to the charm of the houses, and 
do not fulfil some utilitarian purpose. With four- and five-room houses averaging 
from /900 to ;^i,ooo each, this, although much to be regretted, can hardly be taken 
•exception to ; but, as has been frequently pointed out, concrete lends itself particu- 
larly well to artistic treatment without any extra expense whatever being incurred. 






^fi&ny fujjet 




li')i)irstcet anjie 



Wa// /ret abatit- 3 <> (enn-rj 






Fig. I. 



•64 



E 



CONSTBUCTICJSA 
ENGTNEERING 



All 



NEW METHODS OF CONSTRUCTION. 



This result is obtained in a variety of ways, some rather comphcated and some extremely 
simple. 

A very simple and ingenious method is used in connection with the " Spade " 
system of shuttering, invented and patented by Mr. A. L. Woodward, of Ardmay 
Hotel, Surbiton. As will be seen in Fig. i, the shuttering consists of pieces of hard- 
wood held together and kept at the required distance apart by steel angles. When 
a cavity wall is being built, a core of two sheets of steel is inserted, and held in 




Merftoo OF SecL//f/r/c 7Jl//\/4 



Fig. 2. 

position by distance blocks and a centering gauge. The shuttering is kept true as 
the succeeding courses are being built by temporary ties being placed across the last 
completed course, and removed when the shuttering is removed. Wall ties are built 
in at each course as the work proceeds. Each course is built its entire length at one 
operation, so that there are no vertical joints. The shutters are made in four lenoths, 
between 4 ft. 6 in. and 3 ft. 2|- in., and combinations of sets of these shutters will give 
several hundred different dimensions between 3 ft. zh in. and 50 ft., so that there 
is no difficulty in working to different plans. 

Perhaps the most interesting feature of the system is the method adopted for 
obtaining various exterior finishes. Fig. 2 shows the method of obtaining a tiled 
surface without any labour being required beyond that necessary to build the wall. 
The tiles are placed inside the shuttering and held in position bv strips of hoop iron 
while the concrete is being filled in ; when the shuttering is removed they, of course, 
adhere to the wall. In a piece of walling which we had an opportunity of inspecting 
tiles had been built in this manner as a surround for a fireplace, and appeared to be 
quite satisfactory. On another section of walling a mould had been used in the 
shuttering wliich gave the appearance of ordinary brickwork, properly pointed, which 
had not been touched after the removal of the shuttering. To give the appearance 
of rough-cast a piece of ordinary matting is used inside the shutter. By these methods 
excellent reproductions can be obtained of stonework, and even weather- boarding, 
without incurring any extra expense or labour beyond placing the mould in position 
inside the shuttering. This system eliminates all supporting piers, posts and stmts, 
whether permanent or of a temporary nature, and the shutters can be erected to the 
recjuired dimensions without the aid of measuring instruments or gauges. Tlie 
system will shortly be used by two piibli<- bodies in conneclitMi with housing schemes. 



05 



NEW BOOKS. 



iCDMMTEJ 



NEW BOOKS 

AT HOME AND ABROAD. 

A short SMHiz/iflcy of some of the leading books which have appeared duriny 
the last few months. 



Reinforced Concrete Design. Vol. II. 

Practice. By Oscar Faber O.B.E., D.Sc, 
A.M.Inst.C.E. 

London : Edward Arnold. 246 pp. demy tJvo. i8s. net. 

Any publication upon Reinforced 
Concrete by Dr. Faber deserves careful 
consideration by structural engineers 
because he is one of the comparatively 
few engineers who have had the advantage 
of advanced theoretical training and 
scientific research combined with consider- 
able practical experience under commer- 
cial conditions. The present book consists 
of an extended treatment of certain por- 
tions of the original book on Reinforced 
Concrete Design which Dr. Faber wrote 
jointly with Mr. Bowie some years ago. 

Dr. Faber liolds strong views in particu- 
lar upon two problems arising in rein- 
forced concrete design : one of them is 
concerned with the bending moments in 
columns arising from monolithic construc- 
tion, and the other is on shear stresses. 

The present book consists principally 
in an extension of the treatment previously 
given for continuous beams and column 
bending moments. 

The first part of the book (122 pages) 
is devoted to the determination of bending 
moments in beams for various arrange- 
ments of span and conditions of loading ; 
the formulae are derived not from the 
The:>rem of Three Moments with which 
students are now being made familiar 
but upon what may be termed slope 
formulae. '.The present writer is prej udiced 
in favour of the " Three Moments " and 
thinks that Dr. Faber 's book would have 
been followed more easily if this treatment 
had been given first. This part of the 
book is an excellent piece of work and 
should save much time on the part of 
designers who previously attempted accur- 
ately to consider continuous beams and 
many errors in designs on the part of 
those who previously used only so-called 
" practical " rules. The use of " practi- 
cal " rules is commonly the refuge of the 
inefficient. 

Part II deals with column moments 
and explains at greater length than 
formerly the methods of taking account 
of them. Dr. Faber states that " the 
author has heard people argue that if they 

66 



design beams without reckoning on the 
stiffness of the columns, there is no need 
to design columns for bending " and that 
" some so-called specialist firms design 
without taking their factors into account, 
some so-called specialist firms also from 
time to time pay for structures which have 
unaccountably collapsed." 

We hardly think that this innuendo 
is well placed in a scientific treatise, 
especiallv as it is not supported by evi- 
dence of collapse which has been proved 
to be due to bending stresses in the 
columns. Dr. Faber would be doing a 
great service to reinforced concrete 
designers if he could persuade them by 
verified facts that provision for column 
bending moments in design is essential. 
The present writer believes that it is a 
fact that in by far the greater number 
of the reinforced concrete structures 
which have been erected in this coimtry 
and America no such provision has been 
made. With the working stresses at 
present emploved, therefore, it does not 
appear evident that the present methods 
of design are dangerous. If it is sug- 
gested that higher working stresses 
should be allowed on the columns when 
provision is made for bending stresses, 
then the problem is a different one. We 
understand that Dr. Faber is in favour 
of adopting higher stresses when second- 
ary stresses are calculated, but we do not 
find any reference to this point in the book. 

In Part III of the book we have first 
a chapter giving tables of properties of 
standard columns and beams ; then a short 
but good chapter on live load allowance for 
rolling goods. This is followed by a chap- 
ter en Shear Resistance incorporating the 
results of Dr. Faber's researches on the 
subject. There are a number of Appen- 
dices, and finally the London County 
Council Regulations are given with a 
short note upon four points upon which 
revision is considered desirable. 

The book is one which every reinforced 
concrete engineer should study ; it gives 
designers access to tables which save 
much time in calculations and which 
must have involved the author in many 
hours of laborious work. 



E 



CONSTRUCTIOTM. 
EMGTNEERING 



m 



QUESTIO^'S AXD AXSWERS. 



QUESTIONS AND ANSWERS 
RELATING TO CONCRETE 

In response to a very general request we are re-starting our Questions and 
Answers page. Readers are cordially invited to send in any questions. These 
questions icill be replied to by an expert, and, as far as possible, they icill be 
answered at once direct and subsequently published in this cohimn for the infor- 
mation of our readers, where they are of sufficient general interest. Readers 
should supply full name and address, but only initials will be imblished. Stamped 
envelopes should be sent for replies. — Ed. 



Question. — J. L. writes: — In the issue of 
October, page 701, Chap. Ill, " Concrete 
IN Theory and Practice," you give an 
■example 6 in. slab, 2^ ft. span, 12 ft. c.c. 
or ID ft. between beams. You refer to 
your table August issue, p. 567, with a 
view to showing its use. At the end of 
clause ^1, p. 701, October issue, you say as 
jollows : "Though our slab (6 in. depth) 
is not quite the requisite thickness {meaning 
7-2 in the table) this is more than 

■COMPENSATED BY ITS WIDTH BEING MORE 

THAN REQUIRED. / Cannot follow the 
meaning of this, seeing that the example 
.given is 12 ft. wide or 10 ft. between 
beams and the table specifies 34-9 ins.; 
■the distance between beams in the example is 
10 in. or 108 in. Will you kindly explain. 

Answer. — We have read this question 
•several times and there are parts of it 
which we do not think are clearly ex- 
pressed. The article sa3-s that though 
the slab 6 in. thick is not quite the 
requisite tliickness — meaning 7-2 in. as 
shown in the table — this is more than 
compensated by its width being more 
than required. The table shows that a 
width of 34-9 in. is required, that is, 
something j u.st under 3 ft. o in., and if we 
take as the permissible width a slab one- 
third of the span as recommended, this 
would give us something over 8 ft. o in., 
which is, of course, mucli more than the 
3 ft. o in. required. The slab in this 
■connection acts, of course, as the compres- 
sion member of the beam and what is 
required is a compression member which 
will carry a certain load or total compres- 
sion, and it is surely clear that a .slab 
■8 ft. o in. wide, 6 in. thick will carry a 
larger compression than a slab 3 ft. o in. 
wide, 7'2 in. thick as called for bv the 
table. 

Question. — May I take advantage of 
your " Questions and Answers " page to 
inquire the meaning of the terms" Natural " 
cement, " Artificial " cement and Portland 



cement, and wherein lies the difference, 
if any, between these products ? 

Answer. — In replying to these ques- 
tions we will reverse the order and take 
Portland cement first. 

Portland cement is a carefully manu- 
factured product made from minerals 
containing lime, silica and alumina as 
the principal ingredients. The process 
of manufacture is divided into three 
stages. The raw materials are first 
intimately mixed by mechanical means 
in absolutely correct proportions, and 
the mixture ground exceedingly fine. 
The second process is the calcination 
of the raw materials at a high tempera- 
ture in order to bring about a perfect 
chemical combination of the three ingredi- 
ents. The calcination is carried on to 
incipient vitrifaction and results in a 
cement clinker. The third stage in the 
process of manufacture is the grinding 
of the clinker to an impalpably fine 
powder. This powder is Portland cement, 
and only when the whole of these three 
processes are employed is the product 
entitled to be so named. 

Artificial Portland cement is a term 
formerly used to differentiate the scien- 
tifically manufactured article as de- 
scribed above from the " natural " 
cements which are largely produced in 
Belgium and other countries. 

" Natural " cement, often erroneously 
termed " Natural Portland " cement, 
is manufactured from mineral tleposits 
which exist in various parts of the world. 
The deposits contain lime, silica and 
alumina, the essential ingredients of true 
Portland cement, but in varying propor- 
tions which sometimes do not even 
appro.ximate those required for the manu- 
facture of a sound product. This dcpcsit 
is often burned just as quarrieii, without 
the intimate mixing and proportioning, 
failing which a sound and reliable cement 
cannot bo produced. 

67 



■*TS'*™J?**BB" 




CONCRETE^'^"'^''™""™''^ 



ET^GINf^ERnVG 




?gfta- .iiTil 



A BOOK WHICH SHOULD BE IN THE POSSESSION 
OF EVERY MAN WHO IS IN ANY WAY CON- 
CERNED WITH PILE DRIVING OPERATIONS. 

The B.S.P. Pocket Book 



^ I 'HIS handy Waistcoat-Pocket Book of Reference 
is designed to help and guide the "man on 
the job " as well as the Engineer and the Draughts- 
man. It measures 4 in. x 2 in. x ] in. thick, and con- 
tains 144 pages chock full of useful information, 
technical matter, aids for estimating, mathematical 
formulae for calculations of every description in- 
volved in pile driving operations, metric equiva- 
lents, and a host of hints and valuable tips. 

It also contains full descriptions and specifications 
of steel sheet piling, the most recent Pile Driving 
and Withdrawing Equipment and Contractors' 
Plant; "Zenith" Winches, Concrete Mixers and 
Placing Plants. The book is profusely illustrated 
and minutely indexed. 




Make a note to 
write for a free 
copy. 

—'Arris. 



THE BRITISH STEEL PILING CO., 

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LONDON, E.C.3. 



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CONSTBUtTlONAL 
ENGnVEERlNG — ; 



MEMORANDA. 



— uuii ^lljllb^ 




MEMORANDA. 



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editorial comment. Authentic news will be welcome. — Ed. 



hrs. 
hrs. 
hrs. 



Removal of Forms in Concrete Work. — Concrete, U.S.A., recommends the follow- 
ing periods as representative of correct practice for the removal of forms in summer 
weather where Portland cement of normal hardening rate is used : — 

Concrete mass work ........ 24-48 

in thin sections ........ 48-60 

columns ......... 48-60 

in beams and girders ....... 12-21 days 

in long thin slabs ....... 14-21 days 

In cold weather the period will be more or less protracted according to the average 
temperature prevailing, both before and during the setting periods. No attempt 
should be made to do extensive concrete work with freezing temperatures unless 
proper provision be made for keeping the concrete from freezing during the setting 
process. 

Repairing Concrete Floors. — TJie Engineer states that an ingenious system of 
repairing concrete floors which have got out of shape on account of made ground sub- 
siding beneath them has been developed in connection with the extension of the Royal 
Albert Dock, where a number of large warehouses is being constructed. The floors are 
of reinforced concrete, and as thev are laid short ends of scaffold poles are stood up at 
intervals of 20 ft. or so. When the concrete is set the poles are withdrawn and leave 
holes reaching down to the ground. If the floor remains flat the holes are filled in, but 
if subsidence takes place a portable plant comprising an electrically-driven centrifugal 
pump capable of giving a delivery pressure of about 20 lb. per square inch is connected 
with the holes near the hollow and a mixture of ashes and water pumped in. The 
water escapes by the adjacent holes, the floor is lifted to the proper level, and the 
foundation solidified. 

Aberdeen.— Reinforced concrete culverts, sumps, and pump chamber are being 
constructed on the north bank of the Dee in order to provide an ample supply of 
condensing water to the Ferrvhill power station of the Corporation. 

New Bridge for Paris. — The old Pont de la Tournelle over the Seine, well known to 
visitors to Pans, is now being demolished, and will be replaced with a two-arch rein- 
forced concrete structure. — The Engineer. 

Concrete Houses in Italy and France. — Concrete is being u.sed quite extensively in 
Italy and l-ranc e in tonnection witli the housing problem. Some of the aggregate in 
I'Vance is procured in m tiie old battlefields. Where sand and gravel are not obtainable 
broken brick is used as a substitute. At Lens an American Red Cro.'-s Hospital is 
being constructed of poured concrete, broken brick being the aggregate u.sed. 

In Italy concrete is being employed for an industrial citv for Venetian artisans and 
their families. 

Vancouver Port Development.— Some large works arc now in progress for the 
extension of the dock facilities at Vancouver, B.C. The Canadian Pacific Railway is 
building a new 1,100 ft. pier, with two-storey sheds and the Vancouver Harbour Com- 
missioners liiiNc placed contracts for the construction of a new pier ami slieds. Tiie 

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CONSTRUCTIC3NAL 
RNr.nslEERING — ; 



MEMORANDA. 



latter pier will be 1,200 ft. long by 340 ft. wide, with a shore quay 936 ft. by 350 ft. 
Reinforced concrete piers will extend along the sides and the outer end, with an 
embankment of sand and gravel between. At the middle of the pier, where it will be 
135 ft. wide, there will be four rows of concrete cylinders carrying transverse concrete 
trusses to support the floor of the pier. At the outer end of the pier there will be five 
rows of concrete cylinders, extending the berths into 45 ft. of water. In addition to the 
sheds there will be on the quay a three-storey reinforced concrete warehouse, 200 ft. 
long by 82 ft. wide. The total cost of the work is estimated at 6,000,000 dollars, and 
further developments are under consideration. 

Concrete Curb Bridges. — Instead of cutting down the curb to make an entrance to 
the driveways into private yards, Concrete, U.S. A ., says it is quite general in Monrovia, 
Cal., to build curved concrete bridges over the curb and into the yard. 

Dublin University. Lecture on Reinforced Concrete. — The opening meeting of 
the 27th session of the Dublin University Engineering Students' Society was held 
in the Engineering School, Trinity College, Dublin, on December 10, when Mr. A. D. 
Delap, M.Inst.C.E., delivered the inaugural address on " Reinforced Concrete." Pro- 
fessor Alexander, M.A.I., presided, and there was a large attendance of engineers and 
students. 

Mr. Delap, in the course of an interesting address, dealt with the use of concrete 
in the historic past, and, referring to the specification of materials, explained the 
reasons why cement and steel lend themselves to use in combination. He went into 
the reports of the Joint Committee on reinforced concrete, and described the properties 
of the material as well as the methods used in reinforced concrete work, and the other 
technical details attaching to its subsequent preparation and solidification. He 
alluded to the use of reinforced concrete in piles, and said that the most satisfactory 
method of driving was by a heavy hammer, or, in sand, by water jet. He went on 
to deal with the methods used in pre-cast work. Generally reinforced concrete was a 
material of very wide utility, which came into every engineer's practice. Its use 
was extending every day, and practical methods had advanced very rapidly. In 
conditions where it was a suitable material it was as nearly permanent as they could 
hope any of their structures to be, and a knowledge of the principles of construction 
in this material was an ingredient in the education of every young engineer. 

CONCRETE AND HOUSING SCHEMES. 
East Ham. — Major Williams, 'an Inspector of the London Housing Board, 
recently visited East Ham, and suggested to the Housing Committee of the Borough 
Council that in view of the shortage of bricklayers, the question of the erection of 
concrete liouses should be considered in connection with the Council's housing 
schemes. The Committee accordingly recommended tliat the Borough Engineer be 
directed to submit a report on the matter, at its next meeting. This report was 
received, and as a result the Committee has decided to visit the concrete houses in 
course of erection at Bedford. 

Bath. — The Housing Committee of the Bath Town Council is considering the 
advisabihty of erecting a considerable proportion of the houses to be constructed 
under the Council's housing scheme by special methods of construction approved 
by the Ministry of Health. 

Lichfield. — -It was reported at a recent meeting of tlie Lichfield Rural District 
Council tliat the question of the erection of 400 concrete houses at liilston was under 
consideration, and that a deputation which had visited a concrete housing sclieme 
was very favourably impressed. The Surveyor reported that tliere was not the 
slightest doubt that it was an economical system and produced houses very quickly. 

Wrexham. — The Wrexham Town Council has authorised a firm of contractors 
to proceed with tiie erection of twenty-four in siiii concrete houses. " 

Concrete and District Labour. — The Cwmamman (Carmarthen) Turban District 

Cdiiik il li.is (l(( idcd to i)r()(t'('il with the erection of eighteen houses on the Cilanyrafon 
site. 'I he lioiiscs arc to he l)nilt 1>\- dircil lalxiiir. 

71 



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CONSTRUCTIC3NAl^ 









T70R the last lo years the Victoria Concrete Mixers have 
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The design o{ the first Victoria Mixer was based on sound mixing 
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Progress has ever been our watchword, and embodied in the 
design of our latest 192 1 models will be found the result of our 
vast experience and our determination to enhance our reputa- 
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The illustration on this page shows the Victoria Automatic 
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May we send you full details of this machine, together with 
particulars of our various other models dealing with unmixed 
capacities from 4 J cubic feet up to 80 cubic feet. Why not 
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(MIXER DEPARTMENT) 

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72 



I&g;?i^;g^j.^^ MEMORANDA. 

Ministry of Health and Housing. — In their weekly housing report, the Ministry 
state that for the week ending December 15, 1920, contracts have been placed for 
17,722 houses to be built by special methods of construction sanctioned by the Ministry 
of Health ; 4,658 are in course of erection. Under the terms of the Government Grant, 
4,170 are being built by special methods, of which 2,530 are in concrete. 

There were fifty new housing schemes submitted during the week ended December 
II, bringing the total number of schemes submitted to 11,408. Of these 8,736 have 
been approved and comprise 57,666 houses. 

Concrete Sash Weights. — Owing to the high price and difficulty of obtaining cast 
iron, concrete weights for window-sashes are now being made in the United States. 
They are reinforced to a wire loop, and are giving every satisfaction. 

NEW METHODS AND MATERIALS. 

The following materials and new methods of construction have been approved by 
the Standardisation and Construction Committee :- — 

Gorse Hall Construction Company, Gorse Hall, Nr. Charley. — " P. and T." Sysietn. — A system 
■of concrete block construction with flanges on one end of the blocks which act as bonders and 
•continuous piers in the thickness of the wall for its entire height. 

Multee Construction Co., Ltd., 24, Haymarket, London, S.W. i. — The " Multee" System. — In this 
■system of concrete construction the walls are formed of two pre-cast slabs of standard size, each 2 in. 
in thickness, a continuous 5 in. cavity being formed throughout the length of walling. Each standard 
block possesses four stiffeners, this block being divisible into a f unit possessing three stiffeners ; a 
J unit possessing two stiffeners ; and a -} unit possessing one stiffener. The bonding of these smaller 
units enables the stiffeners to be in alignment from base to eaves, and also at the angles of the building. 

A. Stanley Co.v, F.S.L, 16, Queen Victoria Street, Reading. — Co.x's System. — This system has. been 
•designed for the upper storey in connection with the mass production of a standard concrete cottage, 
no centering or timber being required, and consists of curved hollow concrete slabs 6 in. thick, rebated 
or grooved on the edges and jointed together with cement, the slabs being supported on T. purlins and 
finished with a waterproof coating of cement. 

John Laing & Son, Dalston Road, Carlisle. — Laing's " Easiform " system of construction is for 
monolithic concrete and combines shuttering and scaffolding. A double row of shutters is put all 
round the building and the intervening space filled with concrete 2 ft. high. A second row is then 
placed on and secured to the first and after this is filled with concrete the first row is removed and 
refixed, thus forming the third, and S(5 on to the required height. 

A. Bomgren, Jnr., 26, Old Burlington Street, London, W. 1. — The " Centa " Concrete Blocks contain 
three vertical air spaces, are interlocking, and walls of any width can be formed with them. The special 
feature is that the tops of the blocks are sealed in the process of manufacture, with the result that 
when laid with m )rtar between the courses each air space becomes a sealed compartment. The blocks 
are made in a specially heavy machine, which compresses the concrete to the greatest density. 

TENDERS ACCEPTED. 
Concrete Houses. 

Alcester. — The Town Council has accepted the follmving tenders for the erection of houses in 
brick or approved methods of concrete construction : 28 houses : Alcester Builders, Ltd., .-Mcester, 
£23,996 3s.; 10 houses: H. W. Trout, Kedditch, £9,094 12s. iirf. ; 122 houses: H. Boot & Sons 
(London), Ltd., non-park)ur type " A.i," £801 12s. gd. each; non-parlour type " A.2," £781 7s. 6d. 
each ; non-parlour type " .-^.137," £857 8s. lod. each ; parlour type " D," £920 6s. iid. 

General. 

Ghent. — ^The contract for the construction of two reinforced concrete warehouses for the 
Municipality of Ghent (recently advertised in this cnuntry) has been awarded to Messrs. \'an Kerchove 
& Gilson, of Ghent. 

TENDERS INVITED. 

Skipton. — January 14. For the erection of eighteen houses and road and sewer work, for tlie 
T.C. Council Offices, Skipton. 

Taunton. — January 25. Erection of concrete Bridge over river, for the T.C. Plans, etc., from 
Borough Engineer. 

ToRyUAY. — Jannarv 14. lilrectioii of soventv-fivp concrete houses on a svstem approved bv the 
Ministry of Healtli, Inr tlu- T.C. 

PERSONAL. 

Sir Joliii i'rancis Clevcrton Sneli, MimuIkt of Council of tlio lustitulion of Civil 
Rnginccrs and Past President of the Institution of Electrical I']ngincers, has been 
appointed by an Order of Council dated the 23rd dav of Novemlier, 1020, to be a meni- 
l)cr of the Advisory Council to tiic Coniniiltee of the Privy Coniuil for Scientific aiui 
Industrial Research." 

73 



ME MORA NDA . [CQNCBETd 

TRADE NOTES. 

Floor and Concrete Stone Surfacing Machines. — Two new surfacing machines have 
recently been put on the market in Massachusetts. The floor surfacing machine (made 
in five sizes) is said to surface from 800 to 1,200 ft. of concrete terra/.zo floor finished per 
eight-hour day. The stone surfacing machine is said to be designed to surface either 
natural or manufactured stone slabs or other pieces up to 12 ft. 

Teign Valley Granite Co., Ltd. — Our attention has been called to the concrete 
products manufactured by the above Company at the Trusham quarries. Concrete 
blocks of various patterns, concrete fence posts with struts and strainers, flower 
vases, lintels, sills, etc. are made. The Company have erected many bungalows, 
houses, shops and other buildings, as well as a little village of forty-eight houses with 
shops, all from concrete blocks made at their works. 

An interesting feature of their activities is the construction of concrete poultry 
houses in all sizes and designs, which are sent out ready for erection and with full 
instructions for erection. 

The main object in making these structures in concrete is to economise in the 
use of timber, but of course the further advantage of a more durable structure is gained 
which will cost little to maintain. 

Full particulars of the Company's specialities will be sent on application to the 
Teign Valley Granite Co., Ltd., Trusham, Chudleigh, Devon. 

Portable Air-Compressor. — We have received from Messrs. Millars' Timber & 
Trading Co., Ltd., a copy of a folder recently issued by them, describing their portable 
Petrol-driven Air-Compressor. These machines are complete self-contained units, 
arranged for automatic governing and pressure regulation, and their varied uses, 
including riveting, caulking, drilling, chipping, pneumatic painting, etc., are fully 
illustrated. 

The use of portable self-contained apparatus saves the losses inseparable from 
long air pipe lines, and brings within the reach of man}' users, an economical and 
convenient service of power. 

This folder is obtainable in English, French and Flemish on application. 

NEW COMPANIES REGISTERED. 

Centrifugal Concrete Blocks and Poles, Ltd. (171056), 7, Lower Belgrave Street, London, 
S.VV., Registered October 27. Manufacturers of reinforced concrete articles. Nominal capital, £50,000 
in 50,000 £1 ordinary shares. Directors to be appointed by subscribers. Qualification of directors, 
/lOO ; remuneration £250 each (Chairman £350). 

Zwingler's Damp-proof Walls & Concrete Co., Ltd. (171072), Registered October 27, Stan- 
bridge Road, Leighton Buzzard. Manufacturers of concrete building blocks. Ncminal capital, £5,000 
in 5,000 £1 shares. Directors : H. R. Phillips, " VVemddu," Bathampton, Bath ; F. R. G. Gale, 
Bridge Farm, Stoke Hammond, Bletchley ; and E. Swingler, 6, Albany Road, Leighton Buzzard. 
Qualification of Directors, £50 ; remuneration, £50, to be divided. 

N0RTHFLEETT1LE& Concrete Co., Ltd. (171,517). Registered, November 19. 27, Queen Victoria 
Street, London, B.C. Manufacturers of tiles, concrete, cement, bricks, etc. Nominal capital, £10,000 
in 10,000 £1 shares. Directors : F. T. Fisher, W. C. Palmer, \V. G. H. Wright and S. A. Bray. Qualifica- 
tion of directors, one share ; remuneration to be voted by Company. 

John Cobhams, Ltd. (171,664). Registered, November 26. Builders' and Cement Merchants. 
Nominal capital, £2,500 in 2,500 £1 shares. Directors to be appointed by subscribers ; qualification — 
one share; remuneration to be voted. Subscribers: H. P. J. Rammell, Whitton, Twickenham, and 
H. W. Wolfe, 5, Denmark Terrace, East Finchley. 



RECENT PATENT APPLICATIONS. 

141,663. — F. Girlot : Building blocks for hollow 153,491. — C. J. Ross: Concrete building slabs. 

walls. 153,633.— W. E. Clifton and J. S. Ewart : Con- 

153,102. — ^T. .\. Locan &D. E. Landale : Concrete crete building construction. 

construction. 153,670. — T. Sutchffe : Moulds for manufacture 

153,208. — H. P. Brown : Mixing and placing of building blocks. 

concrete. 153,754- — J- C. Beswarick : Hollow concrete wall 

153,417. — K. Yamaguchi : Shuttering for con- construction. 

Crete walls. 153,829. — P. Lauset : Marline for cleaning cement 

153,433. — J. Ward: Artificial stone manufacture. from planks. 

74 



CONCRETE 

AND 

CONSTEUCTIONAL ENGINEERING 



Volume XVI. No. 2. London, Febri.wy, 1921. 

EDITORIAL NOTES. 



THE CONCRETE INDUSTRY. 

In the concluding portion of his Presidential Address at the Concrete Institute, Mr. 
E Fiander Etchells outlined a proposal which had been under the consideration 
of the Council for the formation of a special class of membership to mclude such 
individuals as clerks of works and foremen, it having been felt that less risk 
would be involved and confidence given to employers if the^- knew that men of 
this type who were members of the Concrete Institute, had had to pass some form 
of examination which gave them a status in regard to the supervision of remforced 
concrete constructional work. 

This proposal embodies an idea which has long been in our own mind and 
which we hope to see materialise. 

In view of the enormous development of concrete work during the last lew 
years and the prominent place it now takes in all forms of construction, we are 
strongly of opinion that the time has come when the industry should be properly 
organised and a new trade or craft formed— that of the skHled concretor and 
block-setter. Such a body would in time have its own grades and develop on 
its own lines as other trades have done. 

To all who have been in any way connected with the direction of concrete 
operations, the need for greater and more systematic education in this class of 
work has long been obvious. If this new type of mechanic is to come into organ- 
ised being, his education must not be left to chance ; preparation for his advent 
must be made by a carefully-thought-out scheme of instruction, not only on 
theoretical, but on practical lines. True. Technical Institutions introduce 
concrete as part of their engineering courses, but we want to see more than this ; 
^ve want to see in the curriculum of every Technical School and Institute, both 
senior and junior, concrete regarded as an independent subject and courses 
arranged in both theory and practice, for, in order to secure thorough efficiency 
and intelligent workmanship, the two must go hand in hand. 

• Such courses as we have in mind would be carried on on modern Imcs, and 
would include amongst other methods lantern slides and films in order to add 
attractiveness to the subject, visits to concrete works, where the students could 
see the work of concreting in actual operation, visits to exhibitions of concrete 
products where the wide possibilities of the material would be brought home to 
them, and, what is of prime importance, regular practice in all the operations 
necessary for the {iroduction of concrete of the first quality, and in \anous 
forms of constructional work in concrete both plain and reinforced. 



75 



THE CONCRETE INDUSTRY. [CQNCKETEJ 

As, however, the principles and methods of handhng concrete apply to all 
kinds of work — the application of it being the function of the architect and 
engineer, and the moulds, where used, the duty of the carpenter — we do not think 
that the courses for workmen and apprentices should necessarily be very long. 
Probably the whole ground could be well covered in a six months' programme ; 
but whether or not this is found possible the courses would certainly not be an}'- 
thing like so length}^ as those of other trades, such as carpenters or plumbers, 
where instruction has to be given in different kinds of work that the man may be 
called upon to perform. Instruction for concrete work is a comparatively simple 
matter, and, in view of its importance in the building trades, this fact should 
encourage educational authorities to institute the classes we suggest. 

If such a scheme could be carried into effect, safeguards would be provided 
and the foundation laid for thoroughly sound practice in an industry which will, 
undoubtedly, play a far more prominent part in the future than even it does 
to-day. 

MINISTRY OF HEALTH, STANDARDISATION AND NEW METHODS OF CON- 
STRUCTION COMMITTEE"; REPORT ON THE FIRST YEAR'S WORK. 

It would have been consistent with the popular conception of a Government 
department, if it had refused to sanction the erection of cottages, to which it 
was giving financial assistance, in any but the most usual materials. Actually, 
a very different course was adopted by the Local Government Board (now the 
Ministry of Health), for in April 1919 a Committee Was appointed whose terms 
of reference were to consider questions of standardisation in regard to materials 
and structural fittings, and to consider proposals submitted to the Board in 
regard to new materials and methods of construction in connection with State- 
aided housing schemes. 

From a perusal of the first year's report, which we now have before us, it 
is evident that the Committee have dealt with the applications which have been 
submitted to them, largely as a result of invitations which appeared in the press, 
in great numbers with particular s3Tnpathy, and approvals have been given to 
systems which co\'er a very wide range. 

NEW METHODS AND MATERIALS. 

The report states that the majority of these applications were for methods 
that employed concrete in some of the manifold forms in which it is suitable for 
the erection of small houses. It would appear that the most frequent faults 
have been : in block construction, a tendency to make the blocks too heavy 
and too large for convenient handling, and in reinforced construction an inability 
to build with sufficient economy to compete commerciall}^ with other systems of 
concrete construction. We are surprised that no mention is made of what seems 
to us a serious defect in many of the patent systems that we have examined, 
and that is their lack of flexibility, their tendency to dictate the very form that 
the house shall take. 

The Committee view with particular favour monolithic concrete construc- 
tion, and they consider that where suitable aggregate is obtainable on or near 
the site this method should prove more economical and more expeditious than 
block or slab construction, which involves more handling and more time in manu- 

76 



r ,.coNyrKucTioNAL l xE]v METHODS OF CONSTRUCTION COMMITTEE. 



facture and seasoning. \\'here blocks are used, the hollow wall constructed in 
two thicknesses and connected with wall ties is recommended in preference to 
the cavity block. 

The report includes an interesting section which deals with rammed materials. 
While not wishing to disparage any attempt that may be made to expedite the 
production of houses, we cannot but feel that, for the most _ part, these efforts to 
revive methods of construction that have, in course of time, been superseded by 
others of greater efficiency are not likely to yield results sufficiently satisfactory 
to justify 'the inevitable risk that must accompany such attempts. Except in 
certain outlying districts, which still remain almost untouched by modern de\'elop- 
ments, the tradition for building in these methods has almost perished. Where, 
however, the tradition still exists it may be worth whUe preserving it. A certain 
saving should certainly be effected by the use of unfired materials. 



THE CONCRETE BLOCK. 

Under the heading of " Building Apphances " the Committee express an 
opinion on a matter that has always been somewhat contentious. They consider 
that the manufacture of blocks by a properly designed pressure machine is more 
satisfactory than hand tamping. Both systems have their adherents. No 
opinion, however, is expressed as to the relative merits of wet and semi-dry 
manufacture. The tendency to-day is certainly for the machine to supersede 
the mould ; the increase in output is sufficient to account for this, and probably 
the only disadvantage which the machine may have over wet mixing, is the risk 
which accrues from the failure to apply sufficient moisture during seasoning. 
It is surprising that although the report favours monohthic construction, so 
little attention is devoted to shuttering, for the success of this method depends 
upon the efficiency and cheapness of the sj'stem of shuttering. It must be capable 
of frequent re-use and yet be adaptable to any plan, it must be light, easy to erect, 
and easy to keep clean. It must be rigid. 

STAXD.\RDISATION OF FITTINGS. 

The work which was performed by the Committee in standardising fittings 
has proved extremely useful. Baths, lavatory basins, water-closets, sinks, gutters, 
rain-water pipes, and many other structural fittings were reported upon to the 
Director-General of Housing, and the necessary instructions for the manufacture 
of the standardised goods issued through the D.B.M.S. In determining upon 
the sizes and shapes of the goods, the question of facilitating transport and econo- 
mising space by " nesting " was considered in connection with such articles as 
baths and gutters, likewise the cost of fixing and of maintenance. 

The report contains several interesting appendices, including a report to 
the Board of Agriculture made in 1797 on pise construction, and a report trans- 
lated from the French on rammed clinker and lime. The Ministry of Health's 
specifications for concrete construction and a complete illustrated list of the 
systems of house construction approved up to April 1920 are also included. 
The rejKMt, which is obtainable at is. 6d. from H.M. Stationery Office, is certainly 
an eloquent testimony to the development that has occurred during the last 
eighteen months in the use of concrete. 

77 



FAILURE OF A CONCRETE FLOOR. [JTONQ^ETS 

FAILURE OF A CONCRETE FLOOR. 

The judgment recently delivered in tlie Scottish Law Courts by Lord Sands, in 
which he awarded ;^i,5oo damages and half costs against a firm of contractors 
for the failure of a concrete floor which they had erected, again emphasises 
the absolute necessity of sound construction, both theoretical and practical, in 
all concrete work. The floor in question, which was designed to carry a load 
of 2 cwt. per square foot, was built towards the end of 1916, and in April 
1918 it was found to have failed. As reported. Lord Sands summarised the 
constructional faults as follows : — " Columbian bars at 2 ft. centres were a very 
weak form of reinforcement ; the concrete was of the poorest description of 
concrete used, and was not of high quality of its own description ; and the 
reinforcement bars were not cranked up over the joists where the tension was 
greatest on the top. He could not find evidence of the success of a single floor 
with Columbian bars and cinder aggregate concrete in such a workshop." We 
know nothing of this particular case other than what has been contained in 
several newspaper reports, but if the above statement accurately sums up the 
causes of the failure nothing but failure could have been expected, and had 
the floor been constructed of any other material on equally unsound lines, failure 
would also have been certain. 

Cases of failure in concrete work are so rare that when they do occur 
they receive wide publicity, to the detriment of the interests of the industry 
as a whole. This is particularly to be regretted, for if concrete work is 
properly designed in the first place, and carried out correctly under competent 
supervision, there is no reason whatever whv failures should occur at all. 



GENERAL NOTE. 

Concrete Roads. — We desire to call the attention of our readers to the book on 
"Concrete Roads" which has now been published, and can be obtained from the 
Publishers, Messrs. Concrete Publications, Limited, at 4, Catherine Street, Aldwych, 
W.C.2. [Price 8s. 6d. post free.) 



78 



r J, constbucticmalI 

L&- EMGlM^y PING — J 



RETORT HOUSE, COLCHESTER. 




REINFORCED CONCRETE 
WORK AT THE 
COLCHESTER GAS 
COMPANY. 



The following is a short description of some of the reinforced concrete work 
carried out for the Colchester Gas Company, under the supervision and m ac- 
cordance with the general plans of Mr. W. W. Townsend, Engineer of the Company^ 
The working drawings for both Retort House and Bunkers were prepared 
by Messrs. Edmond Coignet, Ltd. 

FOUNDATIONS FOR RETORT HOUSE AND RETORTS. 

Owing to the inconsistent nature of the ground it was found necessary to 
provide for reinforced concrete piles and foundations, to support the heavy 
brickwork of the retorts and also the concentrated loads from the steel stanchions 

of the building. , . , , •, .1,^ 

The level of the ground on the site was 4 ft- 4 in. below the yard level, and the 
engineer decided to take the yard level as the top of the foundation work m 
preference to building up from the lower level, thereby reducing the length o 
the heavy steel stanchions and the amount of brickwork required in walls and 
retort bench. This plan enabled the foundation work to be carried out without 
any excavation except where piles had to be lengthened, and it allowed for 
the designing of the concrete walls, capping the piles as beams distributing the 
loads on the piles. Under the retort bench a floor was provided, strongly rem- 
forced, in order to carry the heavy weight of the retort bench between the beams 

capping the piles. , ., ,. • ,• 1 

The whole structure, including the brick walls of the building, is entirely 
supported upon the piles. The retort foundations measure about 67 ft long 
by about 30 ft. 9 in. and include 42 piles. The foundations of the building, 
the dimensions of which are approximately 84 ft. by 64 ft., measured from the 
centre of the walls, contain 28 piles. All the piles were made to a standard 
length of 23 ft. and octagonal in section with a diameter of 16 in. 

The piles were of the usual. Coignet type, namely, with a certain number 
of vertical bars of small diameter, tied together by means of hoops, the end of 
the pile being fitted with a cast-iron shoe. These piles were driven by means 
of a 2-ton monkey worked by a steam winch, mounted on the pile frame which 
was moved in various positions on rails, in accordance with the requirements. 

The piles were reinforced in accordance with the various loads which they 
had to carry and which are as follows : — 

Piles No. I were constructed to carry 40 tons. 

Piles No. 2 were constructed to carry 60 tons. 

Piles No. I were originally intended to be 12 in. octagonal instead of ibin., 

79 



RETORT HOUSE, COLCHESTER. 



[CONCKETEi 




P/L£- FOUNDftT/ONS 



Fig. I. Pile Foundations for Retort House. 
Reinforced Concrete Work at the Colchester Gas Company. 

but the extra quantity of concrete required to make all the piles of the same 
section was small, and it was decided to use the same moulds throughout. 
After the piles were driven to the required set, it was found that owing 




ReINTORCED CONCRETt W OKK Al IHE CuLtHESTER GAS COMPANY. 



80 



RETORT HOUSE, COLCHESTER. 




RETORT HOUSE. COLCHESTER. 



iCDNCBETE] 



to the variable nature of the substratum, some of the piles went clown several 
feet more than others. In this case the heads of the piles were stripjied and the 
top portion was lengthened in situ in order to form a proper junction for the 
reinforced concrete foundation beams. 




1 i^. 4. Showing Pre-cast Bi 
Rlinforcld Concrete Work at the Colchester Gas Compasv. 




Fig. .V The Finished Bunker. 
Reinforced Concrete Work at the Colchester Gas Company. 

In order to give greater stability to the foundations supporting the stanchions 
and brick walls of the building, the reinforced concrete beams were provided 
with a footing 4 ft. wide. 

The whole of the reinforcement of the beams and slabs was composed of 
round bars of mild steel. Owing to the considerable loads coming upon the 

82 



n 



CONSTPUCTIONA 1. 
E-NGIMEERING — , 



COKE BUNKERS, COLCHESTER. 



''i ij 3 >^' ^ . "' Id ii B d il 





BUNKERS. COLCHESTER. 



ICDNCl^i'EJ 



slabs of the retort foundations, 
necessary to provide a meshwork 
up the compression. 



It was 

of bars 

to take 

The bars of the beams were linked to- 
gether by means of the usual type of stir- 
rup. 

The work was carried out by Messrs. 
Walter Jones & Sons, of Westminster. 





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COKE BUNKERS. 

A row of coke bunkers also designed 
on the Coignet system was erected along- 
side of the retort house. 

The general dimensions of these low 
level bunkers are 66 ft. in length by 
20 ft. 8 in. in width, measured from the 
centres of the columns, the total height 
being 13 ft. 2 in. above the level of the 
ground. 

The object of these bunkers is for the 
storage of the coke coming from the retorts, 
and they are capable of containing 
approximately 500 tons of coke. 

An interesting feature of this work is 
due to the fact that all the beams on the 
top of the bunkers were pre-cast and placed 
in position by means of a crane. The 
advantage of this method of procedure was 
that no centering or scaffolding was required 
for the making of these beams, which were 
all moulded on the ground in a very eco- 
nomical manner. These pre-cast beams 
measured i ft. in height by 2 ft. 6 in., and 
they were composed of tM'o small longi- 
tudinal beams 12 in. by 4 in., supporting 
a slab 3 in. thick. The object of these plat- 
forms is to carry the rolling load of coke 
wagons w^eighing about one ton each in- 
cluding the load of coke. 

The whole of the reinforcement in the 
bunkers was composed of round bars of mild 
steel and the reinforced concrete pillars 
were supported by means of piles. Each 
hopper is fitted with two openings for the 
discharging of the coke into the trucks. 

The work was carried out by Messrs. 
Peter Lind & Co., of Westminster. 



84 



ir CONSTPUCTICSMAIJ 
fe. ENGITMEEKING — j 



SHEARING STRESSES 




1 



SHEARING STRESSES IN 

RECTANGULAR REINFORCED 

CONCRETE BEAMS. 

. By ALFRED FYSON, M.Inst.CE. 
{Concluded.) 



1 



^ 



The first part of this article appeared in our January issue, page 14. 
While we have much pleasure in publishing the following thoughtful and 
original article, it must not be supposed that we are in agreement with the conclu- 
sion arrived at, and, in point of fact, we publish in this, issue some comm,ents 
on some of the points raised in Mr. Fyson's article. — Ed. 

Diagonal Tension, etc. — Thus far in these investigations there have been given the 
intensities of the internal direct horizontal stresses at a certain section, and the means 
of determining the internal tangential stress intensities at any point in that section ; 
as both kinds of stresses are distributed over the material at the given point simul- 
taneously, it is necessary to find the resultant effects due to their combined action, and 
those resultant effects may be deduced as follows : — - 



Jion^nfa/__Ljj2e^ 



b q'32 4l/bs^ ^r 




X 



q'324/ /bs- 
^(force V($ 2/ /ds) 

In Fig. 6 consider ac as a side of an oblique plane, suppose it drawn at any desired 
inclination through some point in the depth aa^ of the beam at which it is required to 
find the resultants of the stresses known to be acting there, and let that point be 
represented by the small rectangle Fig. 5 near to where oa„ is cut by the plane ee' ; 
let ac, Fig. 6, be bisected at O and ON be drawn normal to it making an angle Q with the 
horizontal line X^X, ac itself having the inclination with the horizon. About ac 
as a diagonal let the rectangle abed be constructed, that rectangle is supposed to be 
the small element in the depth of the beam against and through which stresses already 
■calculated are acting, and its diagonal ac represents a side of the plane on which the 
resultants of the combined known stresses are required ; with the undefined incUnation 
•of ac as drawn in the figure it is found that the length ad is equal to one-half ab. 

85 



ALFRED FY SON. [CDNCBETEJ 

Each known stress acting on the element abed is to be resolved into forces or 
stresses through the lines ON and ac, the former denoting direct and the latter shearing 
stresses. The depth ab of the element is supposed to be unity, or say i inch, and its 
breadth also i inch ; the stress intensities, which are at lb. per square inch, may be 
supposed to be forces acting normal to the face ab and along the faces ab, cb. 

The known forces or stresses at the intersection of aa„ and ee', Fig. 5, are as follow: — 

7=250 lb. acting at right angles to ab .... vide [Fig. 6) ) 
^=32-41 lb. acting along the line ab . . . . ,, (7A) > (8) 

q-=r2=i6'2i lb. acting along the Une cb . . . . ,, (vii) ) 

The explanation of the term q^2 = i6-2i lb. in (8) stated briefly is this: — Static 
equilibrium demands that the opposite moments due to the two pairs of tangential 
couples shall balance. Therefore, in the element abed, Fig. 6, as c6=one-half ab- 
then the tangential force along cb equals half that acting along ab, the intensity q being 
the same on each face of the rectangle. 

The force acting along cb is then : 

cb q 32'4l 

OX -;=-=-— ^=i6-2 1 lb (vii) 

a6 2 2 ^ ' 

The simple work of decomposing each of the forces in (8) into components through 
ON and along ac will not be detailed here, but only the results, and they are to be found 
in [viii), following the order as given in (8) : 



Forces normal to ac through OA''^223*6o4-i4*50 + i4-50=:252'6o lb. 
Shearing forces along the line flc =iii'8o —29-00+ 7*25= 90-05 lb. 



{viii) 



The negative sign in (viii) shows the shearing force to be acting in a direction 
contrary to that of each of the other items along the line ac. As the total results in 
[viii] are supposed to be acting on the oblique plane represented by ac they must be 
divided by that length in order to reduce them to the same uniform intensity of stress 
as that already used, that length is : 

ac= Vfl62+^2^ a/i+(J)2=i-ii8 {ix) 

The total intensity of stress normal to ac acting along ON and the total shearing 
intensity of stress acting along ac are then found as follows : — 

Let p be the normal stress acting on ac at lb. per square inch ; 
Let II be the shearing stress acting along ac at lb. per square inch ; 
Then from [viii) and [ix) the intensities of stresses are : 

^=252-60-^1-118=225-94 lb. per sq. inch \ 

u= 90-05 ~i-ii8= 80-55 lb. per sq. inch j ^^' 

Any other point in the depth of the beam may be treated in a similar manner and 
the stresses p and u found on any oblique plane traversing that point when the values 
for / and q acting on it are known. 

By many writers on reinforced concrete, when p is a. " pull," the stress derived is 
generally known as " diagonal tension." 

The " Greatest Principal Stress " and its " Axis."— In Frg. 6 the inclination given 
to ac is supposed to be at " hap-hazard," and is quite undefined in a general sense,, 
therefore it is a variable, and can have as many different angular positions given to it 
as may be desired, each different inclination producing different values of p and u — - 
the stress intensities / and q remaining constant. 

86 



I&^.^'^SJ^^ SHEARIXG STRESSES.. 

There must, then, be some angle 6 of inchnation OA' which will cause ^ to be a 
maximum, and there must be some angle tp of inclination ac which will cause u to 
be a maximum ; those maxima results could be found approximately by a system of 
" trial and error " on various inclinations — as just shown in {x) — until the required 
maxima were found to some close degree of accuracy. There are, however, certain 
well-known formulas which can be used so as to obviate such approximations, and they 
will now be given. The intensity of the stress p on an oblique plane through any 
desired point is a maximum p„,, when the resultant of all the forces acting on and 
through that plane is wholly normal to it ; then also the shearing stress along that 
plane becomes null. The inclination 6 of the normal to the plane with the horizon, 
due to the maximum normal intensity of stress p^, and the corresponding value of 
/?„j, are found as follows : — ■ 

The angle for ^^ .... tan 20= r^ (9) 



2 



The maximum intensity of stress .^„,=— -j- 'y\ — j +9". . . . (10) 



At the neutral axis where /=o . . . . ^^^=^ and 6=45° . ) 
At the extreme surface where q=o . . pm^f ,, 6= o^ . j 



{xi) 



The above equations are for tension, but by changing / into /„ they can become 
applicable for compression. 

The quantity p,^ as given in (10) is in statics called a " greatest principal stress," 
and its direction of action as given in (9) is called a " principal axis of stress." There' 
are innumerable " greatest principal stresses " throughout the length and depth of 
a beam, and any of them can be found by equation (10) when / and q are known at 
the required points. 

Besides the " greatest principal " there are in beams the " least principal stresses." 
As their name suggests, they are of less importance than the former, and need not be 
dealt with herein, but cases occur in constructions of various kinds in which they have 
to be reckoned with. 

The Maximum Shearing Stress on an Oblique Plane. — The formulae for finding the 
maximum shearing stress intensity z<„, on an oblique plane, and the angle of inclination 
(p of that plane with the horizon, are as follows : — 

In Fig. 6 let ac represent the plane and 9? its angle of inclination — this without 
having any reference to the known inclination of ac as there drawn in the diagram — 

The angle 9? for ?/,„ tan 2(p= — : (11) 

The maximum intensity of stress «„,= '\'^ ( — ) + ?"" .... (12) 

At the neutral axis where /^=o . . tt„,'=q and 95=0° and 90° 

At the extreme surface where ^-o . ?'„,= ,, ?'=45^ • • • •! 

The above equations are for tension, but by clianging / into /^ they can become 
applicable for compression. 

Practical Application of the Formulae (9) to (12). — Proceeding now with tlie 
examination of the actual beam ahcady under consideration, three points in the depth 
of its " tension " part — aO, Fig. 5 — will be selected for stress analyses, viz. : — 

[A) At the bottom of the beam, where the concrete in tension is highlj- strained. 

87 



1 



ALFRED FYSON. [CT^JCKETE ] 

{J5) At about 2 inches above the bottom, just over the reinforcement, wliere 
the horizontal and shearing stresses are both considerable. 

(C) At about 2 inches below the neutral axis, where the " diagonal tension " 
may be equal to or greater than the ultimate stress of the plain concrete. 

At [A) . . . Here/ is found to be 295 lb. per sq. inch, and q—o. 

^ /By equation (()) . tan 20 =0 ^295=0, whence 20 =0 and 0: 

.2 I 



{xiii) 



[xiv) 



g [ .. .. (10) . A,. - f+ V [-) +0-/-295 lb. persq. in. J 

W) (' ,, ,, (11) . tan 293=295 4-0^ CO, whence 292=90' and (p=45°\ 
.S I 

J .. ., (i^) . "„.= '\/("^-) +0 = ^ = 147-50 lb. per -sq. in. r 

At {B) . . . Here/is found to be 250 and q (by equation 7A) is 32-41 lb. per 
sq. inch. Worked out by equations (9) to (12) as in [xiii) and [xiv) the results are : — 

(For tension d^y° 16' , . . p^^2^^'i^ lb. per sq. in. ... (xv) 
I For shearing 9? =3 7° 44' . . Zf„=i29-i3 ,, ,, , (xvi) 

At (C) . . . Here/ is found to be 180 and q is found to be 30 lb. per sq. in. 
Worked out by equations (9) to (12) as in [xiii) and (xiv) the results are : — 

(For tension 0^ 9° 13'. . . /)„^ 184-86 lb. per sq. in. . . . {xvii) 
(For shearing 99^=35° 47' .. . «„== 94-86 , ,, ... [xviii) 

With respect to the stress of 184-86 lb. per sq. in. — the diagonal " ten.sion " 
at (C) — it is practically equal to the ultimate stress of the plain concrete intension. 
That ultimate stress, taken to be about 185 lb. per sq. in., has been deduced for 
present purposes from the breaking strength of a plain concrete beam carried out by 
Dr. Faber at the same time as he experimented on the beam utilized in these investiga- 
tions and described in Fig. 4. 

Adhesion of the Concrete to the ReinJorcement. — The horizontal shear at the 
reinforcement is found b}? multiplying the " stress due to reinforcement " in [vi) by B 
the breadth of the beam. 

Thus the stress per inch run of reinforcement=i 1-36x8 =90-88 lb. . {xix) 

The rods being two in number, and the diameter " ^ " of each being J in., then on 
the surface of each rod — • 

The adhesion intensity ^90-88-^2 tt (^=19-29 lb. per sq. in. ... [xx) 

The foregoing equation [xx) gives the mean stress, the maximum at some part of 
each surface is no doubt considerably greater, but whatever it is, it seems probable 
that in a rectangular beam under ordinary conditions the ultimate adhesive stress 
would never be reached so long as the beam remained unruptured. 

Summary of Stresses at the First Rupture. — Collecting the values of the various 
kinds of stresses given by equations (xiii) to [xx) acting at the sections a^, Fig. 5, and 
to one or more of which the first rupture of the beam was due, the main results are 
given in (13) as follow : — 

Greatest direct horizontal stress in tension . , J ^295 lb. per sq. in. by (3) '\ 



" Diagonal tension "justabove the reinforcement. />„ =254-13 ,, 
,,2 ins. below the neutral axis . />,» ^184-86 ,, 

Greatest tangential stress q =32-41 

,, shearing stress on an oblique plane . . u^ ==147-50 ,, 

,, horizontal shear on each rod (90-88-^-2). =45-44 lb. per lin. 

,, " adhesion " stress ^19-29 ,, ,, sq. 



(xv) 
(xvii) 

(7A) V(i3) 
{xiv) 
[xix) 
{xx) 



An inspection of the items given above in (13) shows that with the exception of the 



E 



coNSTcucTioNALl SHEARING STRESSES. 

EaMGTNEEJilNG ^-. 



first three, each stress is well within its ultimate Hmit ; and of the first three only the 
first and third need consideration. The first rupture, therefore, was due to a direct 
stress on the concrete of 295 lb. per sq. in., or to a diagonal tension of nearly 185 lb. 
per sq. in. This apparent anomaly, that a less stress might produce rupture sooner 
than a greater, is due to their relative positions, for it is to be remembered that concrete 
when " protected " by the reinforcement always exhibits greater strain than in its 
plain state. In the present instance the material 2 ins. below the neutral axis is no 
doubt sufficiently near to the reinforcement to be influenced to some extent by its 
" protection," and would therefore be able to withstand a stress of more than 185 lb. 
per sq. in. without rupture. In deeper beams, however, the ameliorating influence 
of the reinforcement, in similar relative positions, would diminish as the depth became 
increased. The first rupture in the beam was therefore due to the horizontal direct 
tensile stress at the bottom of the concrete of 295 lb. per sq. in. ; and such stress, as an 
ultimate limit, appears to be fairly consistent with stresses deduced from many examples 
of beams of a similar character. 

So far as stresses due to direct shear are concerned they appear to be of compara- 
tively small intensity, and in ordinary rectangular beams the first rupture is probably 
never due to shear itself nor to the sUpping of the concrete on the rods. The ultimate 
strength of concrete in shear appears to be difficult to obtain by experiment, for 
authorities do not agree, even approximately, as to the limits to be assigned to that 
strength. But if the results of theo^y^ as given by equation (12), are to be rehed on 
for practical purposes, it would appear that the- strength of concrete in shear would 
not be less than half its ultimate strength in compression. At or near to the neutral 
axis, however, the hmit of the ultimate shearing stress intensity cannot be put higher 
than that of the ultimate tensile stress hmit allowed for the concrete in its plain state, 
for there p„ =q and p„ cannot be greater than the ultimate hmit of / as supposed in 
its plain state. 

In the foregoing investigations certain stresses have been employed for the 
calculation of the moment of resistance of the beam (vide Fig. 5) ; they include the 
value of the concrete in tension, and are believed to be fakly in accord with actual 
results at the first ascertained rupture. It is not, however, of so great importance to 
know that those represent the true actual stresses as it is to know that some such 
similar stresses are always to be found and do really exist in all cases of flexure ; for 
with such knowledge the accepted theoretical principles which govern the determination 
of the shearing stresses can be employed so as to produce rehable and rational results ; 
without such knowledge any reliable or rational determination of those shearing 
stresses is rendered perfectly hopeless and impossible. 

As the means for finding the weak and critical points in the depth of a beam, due 
to shearing stresses, have now been given at some length, it may not be out of place 
to offer a few remarks as to the means usually employed, and those which might 
possibly be employed, for strengthening and overcoming those weak and critical points. 

Web-Rein£orcements, Stirrups, Inclined Bars, etc.— The capability of a reinforced 
concrete beam to remain unruptured during flexure is dependent not only on the 
power of the concrete to remain intact whilst resisting the horizontal tensile stresses, 
but also on its power to remain intact whilst resisting the effects of " diagonal tension," 
or that combination of horizontal tensile and oblique shearing stresses existing in 
the concrete between the reinforcement and the neutral axis. In order to resist the 
effects of " diagonal tension " various auxiliaries are adapted to the reinforcing bars 
and they take the form of vertical, inclined and curved bars and rods called " stirrups," 
the ends of the main bars themselves being often " hooked " or bent up : any such 
arrangement is generally known as " web-reinforcement." 

There are numerous forms of " web-reinforcements," each different arrangement 
being designated a " system." Some of the " systems " are fairly simple in appearance 

89 



ALFRED FY SON. KOSCKETEi 

and application, and some of them very complex in both. There are perhaps nearly 
as many different " systems " as there are different forms into whicJi the metal can 
be bent, and for each " system " there appears to be some claim to superiority over 
any other. Seeing that the duty of a beam is generally of a simple nature — merely 
to support with due safety a vertical, and often stationary, load of known weight — - 
it seems rather surprising that some form of web-reinforcement has not been evolved 
which would definitely prove its superiority both as regards theory and practice. 
It is certainly one of those instances in construction where it is desirable that theory 
and practice should be fairly in harmony, but at present no well-defined theory has 
yet been advanced which has obtained general acceptance, and as regards practice 
there exists a " commercial " side to it which will be difficult to overcome until rational 
theory has proved and established itself. Faihng the assistance of theoretical guidance, 
the stresses and strains on the various pieces constituting a system of web-reinforce- 
ment are not amenable to rigorous mathematical treatment ; recourse is therefore had 
to the results of experimental data. From those much information is gleaned as to 
what is happening when a beam is well ruptured or at the point of complete destruction. 
Unfortunately, but little is to be gleaned from those data as to what is happening just 
before ruptures commence — a very important period — or when the beam is carrying 
its maximum safe load. Stresses on the pieces at the " safe load " evolved from those 
as empirically deduced from the breaking down load can only be considered as intelli- 
gent conjectures, for the ultimate load on a beam of any material is always found to 
be an erroneous criterion on which to base stresses induced by inferior loads. Some of 
the systems of web-reinforcement show, in tests, very high load-carrying power over that 
of others, when a beam is carried to total destruction ; but it must not be inferred from 
this that the moment of resistance of a beam which determines its "safe " load can be 
in any degree increased by their employment. Such " safe " load for any " system " is 
limited by the area of the reinforcement, the permissible stress allowed on the metal, and 
the quality of the concrete ; and the duty of all " systems " is to prevent rupture of the 
interior part of the concrete to an extent at least equal to that afforded by the reinforce- 
ment at the exterior part. Looking to the fact that in the design of a beam, sufficiency 
of strength for safety and uniformity of strength for economy ought to be kept in 
view, it seems preferable to employ some simple " system " which will provide a fair 
margin of safety for the working load, rather than some more complex, and probably 
costly, system which can be made to show higher results at the load causing total 
destruction. 

In some cases a beam, near to its supports, seems to develop a certain degree of 
weakness — perhaps chiefly due to friction at the bearings causing concentration of 
stresses — and this it is sought to relieve by bending up the ends of the reinforcing bars 
at soire httle distance from the bearings, up to and over which they are carried. 
This " bending up " of the ends of the bars may sometimes give the desired result, 
but unless it is carefully and judiciously effected it might tend to increase the evil it 
was supposed to remedy. 

The use of vertical stirrups attached to the reinforcement as means of providing 
against the effects of "diagonal tension" is often employed. They are however 
incapable of resisting any horizontal strain — except as mere studs; they can only 
transmit vertical strain and that only in a vertical direction, and they cannot act 
independently of the concrete surrounding them so long as the beam remains a compact 
and unruptured mass. Experiments carried just beyond the first small ruptures in 
the concrete do not appear to show any particular advantage in the use of such stirrups, 
but towards and up to the total destruction of a beam they do appear to be elements 
which tend to increase the ultimate load. As a beam appears to break down less 
suddenly when furnished with stirrups than without them, they may be looked on 
as extra factors of safety. 

90 * 



"7, CONSTRUCTlONAlJ 
& EN01ME.F.R1NC. —j 



SHEARING STRESSES. 



Inclined and curved stirrups would seem to be more in accord with some of the 

incunea a vertical ones. Although they suffer from nearly the 

Tars iti^x^n^-ta. tests appear to show them to be somewhat more 

same disabilities p ^^^ ^^^ supposed to transmit some of the 

f T'sheariM stre es to the remforcement, but that does not seem to be 
internal ==,'^"""8 "tresses to t ^,^^i^ ^^^^^ ^^l^,e ^^ p^. 

Sv dSft'o fSt^dmgffeth "price on the concrete itseH snrroimding them ; 
b,t 'he too upright indfnation and'too great distance apart at which they are usually 

^ ^ ,iri no rlnnbt tend to prevent a maximum etticiency. 
' Tofessor F E Tifneaur^e gives it as his opinion that stirrups, whether vertical 

properties ""^ ^J^^^. .^^^ A N Talbot tested to destruction two large beams 

In the year ^^^ f °f ^^^/^^^-^ f^ lo in. deep, similar in all respects, except 

each 25 ft^long. ^Z^^' ^ "^^ jf,^,^^^^ had some of its reinforcing bars bent up 

that one beam was without stirrups ^na na provided with numerous 

issiissiisss 

:ss^::;-;./?;:^b:at:n^'Xs^^-^-mp^r^^^ 

™t=te;rr=mth^^:^;h:^^'^^^= 
~=rr^nc;^::cori:r-:-:r^:rp^^^^^ 

m ;:rr.orceLnt to a Utt.e above the nentra. axis. J'-^^^^^J--;:™ ^l I 
be attached to the reinforcing bars, therefore the whole ma.s " .'="' "^"- .'" ,i„^j 
L toset properly without any hindrance from unnecessary c--;^'™- ^^ '^^ 
sliort rods or thick wires niight be straight or curved as desired, and P 



ALFRED FY SON. 



[QQNCKETEJ 



function would be to act simply as skewers, each one becoming a nucleus of support 
for the benefit of the concrete surrounding it. 

Another suggested method for assisting the interior part of the concrete to with- 
stand better than in its plain state the effects of direct " horizontal " and " diagonal " 
tension, is by the employment of " expanded metal," which, although it has often 
been successfully used in combination with concrete, has not, it is believed, yet been 
tried in the following manner : — Suppose short sections of a light make of that material 
to be introduced into the mass of concrete and placed vertically and longitudinally 
in it at fairly close distances apart from side to side of a beam, and in depth from a 
little above the neutral axis to about the plane of the reinforcement — care being 
taken that no rigid connections shall be in existence anywhere — the concrete would 
be so much " protected " and strengthened that further " web-reinforcement " would 
probably be unnecessary. 

By the employment of some such " supple " system of web-reinforcement as 
sketched out above, it is anticipated that the concrete everj'where would be maintained 
at its full strength and there would be nothing to restrain its proper and natural 
setting. There would be freedom for the insertion of as much or as little " web- 
reinforcement " as might be desired ; there would be freedom from any interference 
with the main reinforcing bars ; and there would be freedom for the manipulation 
of the various pieces and parts into place during construction. 

Looking at the subject of web-reinforcement in a general manner, it would appear 
that the duty of any " system " is mainly, if not entirely, to assist — by its binding 
and skewering properties — the mass of concrete in resisting the effects of tension, 
whether due to horizontal, diagonal or shearing strains ; and further, from a theoretical 
point of view it seems difficult to consider the members of any such " system " as 
being in some sense analogous to the diagonals of an ordinary open braced iron or 
steel girder so long as the concrete remains intact. 

NOTES ON MR. FYSON'S ARTICLE ON SHEARING 
RESISTANCE OF REINFORCED CONCRETE BEAMS. 

By Dr. OSCAR FABER, O.B.E. 

It is always refreshing to see a man boldly set himself against the accumulated experi- 
ence of a profession, and when, as in Mr. Fyson's case, he is able to present his treat- 
ment with great mathematical skill, his article merits study and consideration, besides 
exciting our admiration and interest. This by no means involves any admission 
that Mr. Fyson's theory or treatment should be substituted for those at present in use, 
as may, perhaps, be gathered later. 

Where Mr. Fyson breaks away is at the outset, when he declines to consider the 
whole tensile stress in a beam as taken in the steel and the tensile resistance of the 
concrete neglected. Mr. Fyson's treatment all assumes that the concrete may be 
called upon to carry very substantial tension, and his treatment only applies to the 
beam before the first hair cracks have occurred. 

Now in practice, hair cracks occur in reinforced concrete structures comparatively 
early. In laboratory tests such as my own to which Mr. Fyson refers, the first crack 
often occurs at about half the ultimate load. But a laboratory experiment is free to 
contract without hindrance as the concrete sets and dries, and to expand or contract 
without hindrance as the temperature rises or falls. 

In structures of magnitude, on the other hand, there is always considerable 
restraint. For example, a concrete floor constructed on brick walls has the same 
tendency to contract during setting, but as the walls are often substantial, and stiffened 
with cross walls, they do not permit of contraction of the floor wthout the formation 

92 



f e^o^yroucnoNAiJ NOTES ON MR. FYSON'S ARTICLE. 

jCi. EMGl>fE.E,RlNG ~^1 

of considerable tensile stresses, and for this reason, actual structures often show hair 
cracks at loads much less than half the ultimate, in fact, they often contain hair cracks 
before any loading takes place. 

It does not follow from this that the stability of the work has been endangered 
by these hair cracks— the w^hole experience of reinforced concrete engineers is against 
such a conclusion, since thousands of structures, after showing hair cracks, continue 
to do all that they were designed for in a perfectly satisfactory manner. 

Yet all such structures put themselves outside the range of Mr. Fyson's treatment, 
though the usual treatment, in which tension in the concrete is neglected, then applies 
in full force, and provided the structures were designed in accordance with this usual 
theory, the cracks can be regarded without concern. 

Another point important in practice is the consideration that for obvious 
reasons the actual construction will proceed in stages, and that the joint between the 
old and new concrete never has more than a fraction of the tensile strength of the 
concrete elsewhere, as shown both by direct laboratory tests and in practice by the 
frequency with which contraction cracks follow the lines where construction was 
temporarily stopped. At all such joints, Mr. Fyson's treatment will have little 
significance for the same reasons as already explained, and yet such joints are a practical 
necessity. 

Mr. Fyson claims that tests to destruction give little indication of the actual 
stresses existing before the concrete cracks. This is true, but I think Mr. Fyson is 
wrong when he goes on to state that only the stresses existing before the concrete 
cracks are material. If one had to choose between the two, surely the stresses after 
cracking are the more important, because these indicate what factor of safety the 
structure has, w^hereas the former, being based on the assumption of tensile strength 
in concrete, though it is known this strength will be lost long before failure, can give 
no knowledge of the factor of safety. 

It is quite true, that when the usual theory is adopted, and tension in the concrete 
neglected, that in some sections the actual conditions will be better, and some tension 
in the concrete may exist, but this only means in practice that the deflection is a little 
less than calculated on the assumption of no tension in concrete. On the other hand, 
to adopt Mr. Fyson's attitude that once a hair crack has occurred, the structure has 
no interest for him, would involve the condemnation of nearly every existing reinforced 
concrete structure which is giving complete satisfaction, and would be almost impos- 
sible to satisfy in practice even if considerations of econom y were completely ignored, 
owing to the cracks due, not to loading, but to contraction, temperature changes, and 
construction joints. 

It would be interesting to know how Mr. Fyson would propose to design a struc- 
ture containing thousands of members in the few weeks which alone are available for 
such design in practice, if the calculation of a 12 by 8 rectangular beam reinforced 
with 2- J in. rods occupies the many pages of abstruse calculations, only a very few 
of which are given in the article, the rest having been calculated by him and only 
the results given. Yet its resistance can be calculated in two lines by any experi- 
enced designer on the usual method, and the results of my experiments, which Mr. 
Fyson quotes from, was to show an almost constant factor of safety over a very wide 
range indeed. 

The above remarks were intended chiefly to apply to Mr. Fyson's calculations of 
Mfhients of Resistance. But they apply equally to Shear. 

I have given a method of design by which the shear resistance due to inclined bars, 
stirrups, inclined compression in the concrete, can be calculated in three lines and 
added together, and have shown that the result agrees with experiments by calcu- 
lating the strength of a very large number of beams, under greatly varying conditions, 
by this method, and then testing the beams and showing that the expected factor of 

93 



NOTES ON MR. FY SON'S ARTICLE. [(jONQaETE 

safety was very consistently obtained. This has practical importance in designing. 
Mr. Fyson, apparently, considers stirrups and bent-up rods, not as adding a finite 
and readily calculable quantity to the resistance of a beam, but " as extra factors of 
safety." I take this to mean that to carry a given load he would want to resist the 
whole shear by diagonal tension in the concrete and neglect the resistance of stirrups 
or bent-up bars. This, of course, would lead to very heavy and extravagant construc- 
tion, and it is safe to say that had the industry designed on these lines in the 
early days, and not on the results of tests to destruction, the present state of the 
industry would never have been reached. 

In conclusion, then, it appears to me that the position is summed up as follows • 
(i) Concrete readily develops hair cracks, due to shock, contraction, temperature 
changes, and loading. 

(2) If its strength were dependent on such cracks not being formed, it would be a 
dangerous material. 

(3) Fortunately, however, it is quite reliable after such cracks have formed. 

(4) The only safe method of calculation is,» therefore, that in which concrete is 
neglected as regards resistance to tension, and to rely on it, as Mr. Fyson does, would 
be dangerous. 

(5) The usual methods of calculating resistance moments, and the methods I 
suggested for calculating shearing resistances, none of them rely- on a resistance to 
tension which will break down long before the structure approaches dangerous condi- 
tions, and so far, no better methods have been shown by experiment or practice to 
give more consistent results. 

MEMORANDUM. 

Expansion Joints in Buildings. — Expansion joints in large concrete buildings 
are discussed by G. W. ]Maker, of the Aberthaw Construction Co., in Successful 
Methods, from which the following is quoted : — ■ 

" Some engineers advise that expansion joints should be provided every 100 ft. 
to take care of the contraction and expansion of structures built of concrete. How- 
ever, there can be found in nearlj^ every city of magnitude concrete structures 300 ft. 
long constructed without expansion joints which have successfullv A\dthstood the 
changes due to variations in temperature and humidity. These structures indicate 
that if proper attention is paid to the method of reinforcement the difficulty can be 
overcome within wider limits than 100 ft. 

Examples can be found of structures 400 ft. long that have shown no severe 
cracks after having passed through the intense heat of two summers and the severe 
cold of winter. 

In general, however, for buildings over three storeys high and over 300 ft. long, 
expansion joints should be provided. These joints should completely separate the 
buildings one from the other, so that the different units will be free to move inde- 
pendently and of their own accord. This should preferably be done b}' means of double 
columns and double beams. The columns may rest upon' the same footing as the 
movement would be practically negligible below the ground. 

" The adjacent column and beam should be cast after the forms for the first 
have been removed. In order to prevent the weather from coming through the space 
between the outside wall columns and the roof beams, a metal, diaphragm should be 
provided of either sheet lead or copper. This should be bent in the form of a " V " 
so as to allow it to expand as the two different units of the building move. The 
joints at the floor level should be protected by angle guards, which prohibit the e^e 
of the concrete from being broken. Sliding plates should be provided to prevent 
the dirt from sifting through to the floor below. 

" Another method of accomplishing this same result in providing a successful 
weather stop for the columns is to cast two grooves in the first section approximately 
3 in. by 3 in., and coating with paint or pitch. In building the next section a tojigue 
is formed by the concrete entering the grooves previously left." 

94 



l^^^jSTBucncgg AMERICAN "FLAT SLAB" TYPE OF BUILDING. 









THE AMERICAN 
^^FLAT SLAB'' 
TYPE OF 
BUILDING: ITS 
ADVANTAGES 
AND DESIGN. 










NTERIOR \'IE\V OF BuiLDIVG FOR THE CON'TIN'ENTAL CaR 
Co., SVRACUSE. 





By A. E WYNN, B.Sc, Assoc. M. Am. Soc. C.E. 

While on a visit to England last winter the writer was struck with the absence of 
reinforced concrete buildings built on the " Flat Slab " system, and was particularly 
surprised to learn that this type of construction was prohibited by the L.C.C. Build- 
ing Code. There is little or no mention given to it in any of the English text-books 
on reinforced concrete. This seems very surprising, to any one from America, where 
this system is so common, and which, in fact, has almost entirely superseded the old 
beam and girder design for certain types of buildings. 

The writer attributes the rapid growth in the use of reinforced concrete for build- 
ings in the United States largely to the adoption of this "' Flat Slab "type of design. 

It is with the idea of giving English engineers some knowledge of the advantages 
and design of this system that this article is written. At this time, in particular, 
when reinforced concrete is being considered more than ever before in England, and 
when economy of construction is of so much importance, the adoption of new and 
economical methods should receive every consideration. 

The first " Flat Slab " building in America was erected in 1903, Mr. C. \. P. 
Turner being the pioneer engineer of this design. Since then its growth has been 
extraordinarily rapid, until at the present time at least 80 per cent, of the new reinforced 
concrete buildings (with live loads of 100 lb. or more per sq. ft.) are built of this type. 

It is used principallj' in factories, warehouses, cold storage plants, garages and 
other buildings where the live load is 100 lb. or over per sq. ft., and where the floors 
are not much cut up by openings. 

Advantages. — -The chief reasons for using it are economic ones. 

Economy in construction is the first consideration. For average conditions it 
is more economical than beam and girder type, and the difference in cost is more 
marked as the live load increases. 

The formwork is much simpler and more rapid, and there is not so much waste. 
There is a considerable saving in storey height and in the total height of a multiple 
storey building, as there are no projecting beams. Due to the absence of beams 
placing of steel and concrete proceed more rapidly. 

Apart from economy in construction there is a saving in cost on the installation 
of the mechanical equipment due to the flat ceiling. An automatic sprinkler system 
can be installed at less cost, and is far more efficient since the flow of the water is 
not obstructed by beams. Shafting, piping, wiring, overhead conveyor systems, etc., 
can all be installed more easily, as tiierc arc no beams and girders with their different 
depths to avoid. 

Other advantages to the owner arc better fire protection, better lighting, greater 
storage capacity, increased safety against overloading of floors, and a better looking 
interior to his building. 

95 



A. E. WYNN. 



ICQNCRETEi 



In case of a bad fire a flat slab building will suffer less than one of tlie beam 
and girder type, as there are no corners of columns and beams, which points are 
always the first to spall and endanger the building. There are no beams to obstruct 
the passage of daylight, and as the windows can be carried up to the underside of 
the floors good illumination can be obtained for the maximum width of building. 
Indirect lighting can be used with the maximum efficiency as there is greater reflection 
of light from the flat surface. 

In a warehouse goods can be stored right up to the ceiling if necessary. Owing 
to the great number of small bars running in several directions, danger of collapse 
from overload is minimized as the stress is better distributed. Most of the misplacing 
of steel occurs in the beams and girders, and as these do not occur in " flat slab " 
design there is much less possibility of misplacement and perhaps consequent failure. 
Also, as all the steel is in plain view it can be more easily and quickly inspected. 




/■/G.J 



General Description. — A " flat slab " floor consists essentially of a reinforced 
concrete slab of uniform thickness, supported symmetrically on columns the tops 
of which are splayed out to form caps underneath the floor. Above the cap there 
may or may not be an increased thickness of slab forming a " depressed panel." All 
loads on the floor are transmitted directly to the columns without the agency of 
beams or girders (see Figs, i and 2). 

The reinforcement usually consists of bands of small bars running from column 
to column, in the bottom of the slab at the centre of the bay and in the top of the 
slab over the column. 

The bays are usually square or nearly so, with the columns spaced about 20 ft. 
apart. The building should be at least three bays wide, if possible. 

Theory. — The actual action of " flat slab " floors is not fully known though 
several analyses have been put forward. The stresses are exceedingly complex so 
that it is practically impossible to work out any exact formulae. 

Fig. 3 will give a general idea of the way in which the slabs act. The lines join 
up points of equal deflection and are in fact contours. It will be seen that inthe 

96 



Tor constbuctkkaU 

L&- ENGIMF-FJING ^-J 



AMERICAN "FLAT SLAB" TYPE OF BUILDING. 



centre of the bay the top surface is concave while over the columns it is convex. 
Detonation of the fibres is equal so that the fibre stresses act perpendicular to the 
SmarSeflection lines. The usual way of resisting these stresses is by placing bands of 
stratht reinforcing bars cutting these contour lines approximately at right angles. 

!t has been foiTnd by numerous tests that the points of inflection he on a line around 
the column head enclosing an area which is between a square and its mscnbed circle. 
The minium distance between opposite inflection points is about 0-5 L and the maxi- 

"^"To^rphfy^hfd^Sgt si^ rbenlrite nfalong the line of inflection is 
zero i? is^ossible to separate the slab into simple parts along this hne and we have 
circular cantilevers at the columns, suspended slabs between columns and a centre 
slTb supported on four sides. In the cantilever portions the stresses act m both a 
adiafand a circumferential direction, and are resisted by bands of bars m the top 
of the slab The suspended slabs between columns are stressed principally m one 
direction and are reinforced by a band of bars in the bottom of the slab. There are 
afso secondary stresses due to shrinkage, temperature changes and cross bending ; 
these are res^ted by a band at right angles and m the top of the slab. The centre 



VJ *» u V> , >- y 

^ .?^ >> <:> "0 ^ '•« ■«, 




V 5! *^ 5^'ij 5 



I 

slab is stressed in all directions and is usually reinforced with two bands at right 
angles in the bottom of the slab. ^1 j. ;o 

^Tn attempting to analyse the stresses mathematically one of three methods s 
usuaUy chosen: (i) dividing the slab into strips and ^-atmg them as continuous 
beams; (2) dividing the slab into circular plates enclosed by he ^^"-^J^ f ^^^^^^^ 
and supported at their centres by the columns and considermg them umformly loaded 
over their areas and peripheries ; (3) considering the slab as a plate ^^PP^f/^ J>^- 
metrically at points. The first two methods give moments and f ^^^^^jf J^\Ye ^'iVen 
ance with those found from actual tests on buildings. These analyses wiU not be giv en 
in this article as they would occupy several pages, and as they are not used m design 
they are of only mathematical interest. 

All formulae used m designing - flat slab " floors are empirical, based on the 

results of numerous tests of actual buildings. They however can be checked closely 

by the first of the above methods. r«Jnfr,rrin£r 

Before giving these formulae we will consider a few of the systems of remforcmg 

in use. 

97 



A. E. WYNN. 



[C DNCRETEJ 



Systems. — The two usual methods arc the " two-way " and the " four-way " 
systems of reinforcing. Until last year these were patented but the patents have now 
lapsed. 

Another method, the S.M.I, system, has probably the best theoretical distribution 
of steel and consists of circular hoops in combination with bars radiating from the 
columns. The steel is rather difficult to place and the system is not so extensively 
used as the first two systems. 

The " two-way " and " four- way " systems only will be treated here as these 
are the two in common use. 





The S.M.I. System, consisting of Ciri hi.ak IIliop; 
Bars Radiating from the Culu-m.ms. 



Truscon System, consisting of Radial Bars over thk 

Column and two Rectangular Bands in the Centre 

OF THE Bars. 




Truscon System. Note Spacer Bars of Tee Section 

CARRIED BY StEEL ChAIRS. 

The bending moment coefficients vary slightly with different building regulations 
and authorities, chiefly in the proportion of the positive and negative moments to 
the total moment. 

The Chicago Building Code is recognized as the authority on " fiat slab " design, 
and is used more than any other. Most other regulations are modifications of this 
Code. The Chicago Code is most conservative and is absolutely safe to use. 

All the formulae given below are those recommended by the Chicago regulations. 

Any of these systems can be designed with or without depressed panels. Depressed 
panels help to stiffen the structure, are more economical of steel and concrete and are 
more often used than not. It will be taken here as standard practice to use them 
and afterwards the modifications in design for slabs without " depressed panels " will 
be given. 

The " Two-Way " System {Fig. ib). — In this system the bands of bars run in 
only two directions. There are two bands at right angles, one in each centre strip 
B, part of the bars being bent up into the top of the slab to provide negative moment 
over the cross bands A. There are also two bands, one in each column strip A, part 
or all of the bars being bent up to provide negative reinforcement over the column 
head. 

The" Four- Way " System {Fig. ia). — This system consists of two diagonal bands 

98 



n 



C0N3TPUCn' 

ENGnsrF.F.p iN( 



lONAIJ 



AMERICAN "FLAT SLAB" TYPE OF BUILDING. 



and two cross bands ; most or all the bars are in the bottom of the slab at the centre 
of the panel and in the top of the slab at the columns, bending up at about the quarter 
points. In addition there are short top bands over each cross band and at right 
angles to them. 

Either of these systems are used according to the preference of the designer. 




The Two-Way System. 




Nbw Buildino for the Haynes .Automobile Compavv, Kokomo, Inu. Typical Four-Way Ststkk. 



The " four-way " is more economical of steel, bars can be used in their full mill length 
and do not require bending as they are small in section and sag from top to bottom of 
slab by their own weight. In the " two-way " the bars are larger in section and have 
to be bent; it is perhaps a little more economical to place and is best suited to heavy 
live loads. 

prom actual tests there is little difference in the stresses developed in the two 
systems. 

General Formula for Square Panels. — These formulae are applicable to either 
system. 



D 2 



99 



A. E. WYNN. 



KO^CBETEJ 



zw=uniform live+dead load per sq. 
L=side of square panel. 
M^=total panel loa.d=wL^. 
/=:thickness of slab. 



ft. /'= thickness of depressed panel. 

c=diameter of col. cap at a point where 

it is at least i^ in. thick. 
d^^side or diameter of depressed panel. 



Then minimum t=-o22XLx\/w, never less than* L/32 for floors. 

,, ,, ,, L/40 for roofs. 

,, >> ,, 6 in. 

c=*225L, angle side of cap makes with vertical always 45 degrees. 
d—not less than L/3. 
In designing we consider a square panel bound by the centre lines, drawn through 
four columns. This is then divided for design purposes into two centre strips B 
and two column strips A, each equal to L/2 in width (see Fig. 4). 

There are two kinds of panels, interior and wall panels. An interior panel mtist 
have at least one adjoining panel on each side, that is, it is continuous on each side. 
A wall panel is non-continuous on one rtr two sides. 




— I / //' ,y -■ 







JSCT/or^/i/l 




r/<s.3 



O 



a 






o 



o 



f¥i/^£L jr^/fj ^<tf*!^S 




BSAfO/r/a />fo/ncrtr Omgis/}/^ 

no.S. 

The bending moment diagram is shown in Fig. 5. 

Design of Two-Way System : — Moments. 

Strip A. — Negative moment for each strip at edge of column cap^ — l'FL/30. 
Positive moment for each strip midway between columns =IFL/6o. 

Strip B. — Negative moment on line of columns for each strip= — H^L/120. 
Positive moment at middle of panel for each strip=PFL/i2o. 
For wall panels use the same coefficients as for interior panels, but increase the positive 
moments in A and B each 25 per cent. 

Distribution of Steel to resist Moments. — Amount of steel to resist bending moment 
in any strip to be area of steel included in width of strip. 



[&g3r^^^t^^ AMERICAN "FLAT SLAB" TYPE OF BUILDING. 

Compression in Concrete. — Width of beam assumed to resist compressive stresses 
over column cap shall be width of depressed panel. 
Example. Interior panel 20 ft. X20 ft. L = 2o. 
Live load=2oo lb. per sq. ft. 
Floor finish=20 ,, ,, 

Allowable stress in steel= 16,000 lb. per sq. in. 

,, fibre stress in concrete for4-moments=650 lb. per sq. in. 

,, — ,, =700 ,, ,, 

punching shear around perimeter of cap = 120 ,, 

D.P.=6o 
Assume thickness of slab ^==8 in. Fireproof! ng=f in. 

^=200+20 + 100=320 lb. per sq. ft. 1^=320X400 = 128,000 lb. 
^='023XLX\/"^ = "023X20X\/320=8^ in. 
c=-225XZ- = -225X20=4 ft. 6 in. dia. rf=L/3=2o/3=6 ft. 8 in. 

^ • ^ ,^ TTTT /^ 128,000X20 J., „ 

Strip A. \-M=WL/6o^ =42,700 ft. -lb. 

60 

effective depth 8^ — 1^=7 in. 

A 2 700 X 12 

Area of steel in band= — ^-^ =5'24 sq. in. Say 14! sq. bars. 

16,000 X -874X7 

TTTT / 128,000X20 Q ,, „ 

— M=WL/io= ■ — =85,400 ft. -lb. 

30 

To find depth of depressed panel : — 
Moment of resistance of slab at D.P. = 70o/2 X6-67 X-396 X 

=803(^)2 ft.-lb. ' 



or ^=V ^''^°° =io-32+i-5 = ii-82, say 12 in. 
^ 803 

Area of steel=— ^^^^^7^77 =7-o2 sq. in. Say i8f sq. bars. 

16,000 X -868 Xio'5 

To obtain these we bend up nine bars out of the fourteen from each side of the 
column, leaving five bars straight in the bottom of the slab. 

These bent bars are to extend to a point J L or 5 ft. beyond the centre line of the 
column. 

128,000X20 
Strip B. |-M=lFL/i20= =21,340 ft.-lb. 

Effective depth =7 in. 

213,400X12 ^ . , . , 

Area of steel=—: — ^^-^ — = =2-62 sq. in, say ii.V in. sq. bars. 

16,000 X -874X7 

_iVf=H^L/i2o=same, say 11^ in. sq. bars. 

To obtain these bend up five or six bars from each side, extending them as before 
3 ft. beyond the column. 

The bars are bent up at the quarter points and are staggered so that alternate 
bars are either side of the line of inficction (see Fig. 6). 

128,000— 3-14 X4-5V4X320 

Shear around Cap= J ^ ^ J /^ J ^ 11^ sq 1,^ 

^ 3-I4X54XIO-5 

__ 128,000-6-672x320 

D.P.=— — — —i;~ — =58 lb. sq. in. 

4X80X7X-874 

Tlie witltli of the bauds will be L/z or 10 ft. This completes the design of the panel. 

lOI 



A. E. WYNN. 



[QONCBETEJ 



A wall panel is designed the same way, only the positive moments are increased 25 
per cent, and against the lintel there will be a half band A. 

Design of Four-Way System. Moments:— 
Strip A . — Negative moment for each strip at edge of column cap = — WL/^o. 
Positive moment for each strip midway between columns = irL/8o. 




Four-Way System showing Inserts for carrying Pipes and Shafting. 




Interior View of a Factory — Without Depressed Panel. 



Strip B. — Negative moment on Une of columns = —PFL/i 20. 

Positive moment middle of panel=lFL/i20. 
As before, for wall panels increase the bending moments 25 per cent. 

{To be continued.) 

102 



r»^ cc(r>J5TB(ytnc»>(Ail 



THE CONCRETE INSTITUTE. 




THE CONCRETE 
INSTITUTE. 

MONTHLY NOTES. 

By the SECRETARY. 




loth. 
17th. 
24th. 



March 3rd. 
loth. 
31st. 



COUNCIL AND COMMITTEE MEETINGS FOR FEBRUARY AND MARCH. 

February 3rd. R.C. Practice Standing Committee, at 4 pm. 

i-eoruary ^ ^^_^^^^ Standing Committee, at 5-30 P-m. 

Literature Standing Committee at 5-30 P-m- 

Finance and General Purposes Committee, at 0.30 p.m. 

Impermeability in Concrete." (Lantern.) 
R C Practice Standing Committee, at 4 p.m. 
Science Standing Committee, at 5.30 p-m. 
Literature Standing Committee, at 5-30 P-m. 
Finance and General Purposes Committee, at 5-30 P-m. 
Council, at 5.30 pm. ^ g 

Ordinary General Meeting, at 7-30 p.m. Paper by Mr bven 

Bylander, M.C.L, entitled " Stresses m Structural Steel. 

RESULTS OF THE EXAMINATIONS. 

The following candidates were successful in passing the Institute's Examma- 

tions in 1920 :— ,, -r. c /tt \ 

For Associate-Membership :-Attrill, Albert Henry, B.Sc. (Eng.). 

Cramer, William. 
Morton, Harry. 
O'CONNELL, Terence Joseph. 
Row Bina Venkatareddy Naranaya (Parts 

I. 'and II.). -c^ T,c 

RouGHAN, James Joseph, B.E., B.bc. 
Senior, Edward Powell. 
Shore, Albert WiUiam (Parts I. and IL). 

Crowther, Fred Sefton. 
ScHOFiELD, Reginald William. 



For Graduateship :— 



EXHIBITION OF CONCRETE AND REINFORCED CONCRETE ARTICLES. 

The Concrete Utilities Bureau has on permanent exhibition at 143. ^;;^^f ^"^" 
Road (cloHo Vauxhall Bridge, S.W.i) a great -nety of Concre^^^^^ 
rnnrrete irticles These may be inspected any day (Monday to tnda> mciusive; 
bet^en ihrhours of 10 a.m. and 4 P-.m- by mentioning the Secretary of the 
Concrete Institute as introducing the visitor. 

103 



THE CONCRETE INSTITUTE. [CDNOaETE] 

CLASSES IN STRUCTURAL ENGINEERING. 

For the information of our Members in general, we are noting here some 
brief details as to Classes, which are held at various Institutes in the subjects 
of Structural Engineering, Concrete and Reinforced Concrete ; — 

Borough Polytechnic Institute, Borough Road, S.E. 

The Principles of Mechanics, on Thursdays from 7.30 to 9.30 p.m. — 

Lecturer, Mr. G. Goodwill, B.Sc. 
Engineering Science. — Lecturers, Messrs. G. E. Draycott, H. A. Boult- 

bee and E. L. Joselin. 
Applied Mechanics. — Teachers, Messrs. Draycott, Boultbee, G. W. 

Bird and F. G. Smith. 
Structural Engineering Drawing and Theory of Structures. — 3rd and 4th 

year work include some Reinforced Concrete work. 

Imperial College of Science and Technology and City and Guilds 
of London Institute, Exhibition Road, S.W. 
Teachers. — Mr. M. G. Weekes, M.Inst.C.E., and Mr. R. Freeman, M.Inst. 
C.E., M.Am.Soc.C.E. (of Messrs. Sir Douglas Fox and Partners). 

London County Council Central School of Arts and Crafts, South- 
ampton Row, W.C. 
Structural Mechanics. — Lecturer, Mr. E. S. Andrews, B.Sc. (Eng.)., M.C.I. 

London County Council, Westminster Technical Institute, Vincent 
Square, S.W. 

Structural Engineering, — Teachers, Messrs. J. Stuart Ker and E. H. 

Sprague. Lecture, Practice and Drawing courses. 
There is an advanced Course in Structural Design in Reinforced Concrete. 
The Design of Steel Frame buildings (with particular reference to the 
requirements of the London Building Acts). Lecturer, Mr. Ewart 
S. Andrews, B.Sc, M.C.I. 

Northern Polytechnic Institute, HoUoway Road, N. 

Structural Steel and Ferro-Concrete. — Conducted by Mr. W. C. Cock- 
ing, M.C.I., in the Senior Day School. 

Mechanics of Structures, Graphical Statics and Ferro-Concrete. — Con- 
ducted by Mr. R. Graham Keevill, A.M.I.Mech.E., M.C.I. , in the 
Evening School. 

University of London : Goldsmiths' College, New Cross, S.E. 

Classes in Structural Design and Theory of Structures, which are included 
in the Mechanical Engineering and Constructional Engineering 
courses. 

University of London : University College, Gower Street, W.C. 

Engineering Drawing and Design.— Professors, Dr. E. G. Coker and 

Mr. H. P. Philpot. 
Civil Engineering. — Reinforced Concrete. Professor, Mr. Ernest R. 

Matthews, A.M.Inst.C.E., M.C.I. 
There is also now in progress a Course of Lectures on Reinforced Concrete 

with practical Laboratory work, which is being conducted by Dr. 

Oscar Faber, O.B.E., D.Sc, M.C.I. 

Wimbledon Technical Institute and School of Art, Gladstone Road. 
A Class of Structural Engineering is arranged here. 

E04 



r 3. CDN5TKUCT10KA11 
\^ Fj«jr.nsfF.F.PiNG -^ 



HOUSING SCHEME, HAYES, 




CONCRETE COTTAGE BUILDING. 
HAYES HOUSING SCHEME. 



The history of housing at Hayes is one of unusual interest, both from the point 
of view of the concrete speciahst, for it shows how concrete has proved ultimately 
successful while other systems failed, and from the point of view of housing 
generally, for already before the war the district was faced with various difficulties 
which it had set out to solve. Seventeen years ago the district was, for the most 
part, agricultural, the only industry being that of stock brick -making. In con- 
sequence of this industry a large number of one-storey cottages were erected for 
the accommodation of the brick-makers from the refuse and shuffs from the 
brickfields ; these cottages remained after the brick-earth was worked out and the 
works closed, and became inhabited by agricultural labourers. 

The first housing survey was made by this Authority after the passing of 
the Housing, Town Planning, etc.. Act of 1909, and it was found that these houses 
were unfit for habitation. Meanwhile the southern portion of the district had 
developed rapidly into a manufacturing area ; it therefore became necessar}- to 
build, and the first housing scheme of 51 houses was begun in 1911, at an average 
cost of £220. The next scheme was to have been begun just before the war, but 
was delayed and not completed until March 1920. 

During the war Hayes developed as a munition centre and some 10,000 
people came to work in the factories, and the shortage of accommodation became 
so acute that in 1915 the Authority sought permission to build, but the cost was 
too high and the scheme did not mature. The need, according to the survey made 
on the passing of the 1919 Act, was 2,000 houses. The scheme prepared in 1915 
was re-modelled and made to accord with present-day standards. The area of 
the site is about 147 acres and the number of houses included on the layout plan 
is 1,255 (see Fig. 1). The first brick was laid by Dr. Addison on February 20, 
1920, and it was then hoped that the contractors. Sir Robert McAlpine & Sons, 
would be able to give a good output, and a large quantity of plant was brought 
on to the site, but it was found impossible to obtain an adequate supply of labour. 

At this point it was decided to employ other methods of construction. It was 
useless to attempt a concrete block construction since the use of the block entailed 
the service of a bricklayer, of whom there was such a shortage. It was agreed to 
erect 100 steel-framed houses on the Dorman Long principle and 100 on some 
other concrete system. Various methods were tried until a satisfactory result 
was obtained, and as these may be of particular interest to those seeking for a means 
of economizing in skilled labour, a short description will be given of each. The 
first comprised the employment of a special mould that was used for casting a 
block " in situ," a semi-dry mi.xture being rmploycd. It soon biH'ame apjxuent. 

105 



HOUSING SCHEME, HAYES. 



[O^NCRETEJ 



HOUSING SCHEME HAYES MIDDX 




Fig. I. Layout Plan. 
Hayes Housing Scheme. 



io6 



r (J, CONSTRUCnCMAn 
l«ENG17MF.'F PING ^<] 



HOUSING SCHEME, HAYES. 



however, that with this system considerable difficulty existed in maintaining 
alignment ; moreover, at first floor joist level it was found that the mould was 




A^/-^oo o^ £ >?£ cr./^q K/-« . 




Fig?. 2 & 3 Fidlcr Sy-stem of Constniction. 
Hayes Housing Scheme. 



useless, and it became necessary to complete the houses by another method. An 
attempt was then made to construct a partly hollow wall with a movable 
mould, but this proved no more successful than the former method. 

107 



HOUSING SCHEME, HAYES. 



iCDNCBETEJ 



!■ UiCL \ 



Ordinary wood shuttering was then tried, and a wall composed of two 
3 in. slabs with a 3 in. cavity, the two leaves being bound by galvanized iron wall 
ties, was built. This again was doomed to failure owing to the high cost entailed 
in erecting and striking the shuttering. The next experiment was with a solid 
wall. In order to overcome the nuisance of condensation it was decided to use 
two mixtures, the outer one being 5 in. thick, and of ballast concrete, the inner 
3 in. thick, and of klinker aggregate. The two portions of the wall were kept 
separate by means of a thin steel plate, which was at once withdrawn so soon as 
the mixture was placed in the shuttering. It was found, however, that there 
was insufficient adhesion between the two parts of the wall, due, probably, to the 
different rate of moisture absorption and of expansion in the different aggregates. 

The shuttering was 12 ft. by 3 ft., fastened to- 
gether by bolts, which of course passed through 
the wall. These were withdrawn as the shutter- 
ing was struck. 

Yet another attempt was made on the same 
lines with climbing shuttering, which consists of 
a double-faced metal shuttering, fixed top and 
bottom by wires. When a section is completed 
the lower wires are cut, and leaving the upper wires 
intact the shuttering is raised. In so doing it de- 
scribes a semi-circle ; the height of the shuttering 
being the radius. This was found to interfere with 
the scaffolding, and was in turn abandoned. 

Before describing the final and successful 
experiment, it would be well to draw attention 
to the original objective, which may have been lost 
sight of by the reader in following the foregoing 
attempts. The first difficulty arose through 
shortage of skilled labour. A system, therefore, 
was required which could be employed by un- 
skilled labour. This ruled out the usual block 
construction. The ensuing attempts failed partly 
from expense, partly from difficulty of alignment, and partly from difficulties 
encountered at first floor joist level. 

The successful system is a combination of two of the rejected systems, which 
by a clever combination overcome all the above-mentioned obstacles. The method 
was invented by Mr. D. C. Fidler, the Surveyor to the Hayes U.D.C., and has 
since become known as the Fidler system of concrete construction. It consists 
of a combination of the concrete block and the " in situ " systems, and the key 
to its success depends upon the invention of a metal wall-tie, which performs a 
twofold function : that of preventing the inner and outer leaves spreading when the 
cavity is filled with liquid concrete, and of rendering the erection of the blocks 
almost fool-proof, since these ties or clips hold the blocks so precisely in position 
that they can be built up by unskilled labour. 

Fig. 2 shows the tie in position ; it will be observed that by means of the 
upwards and downwards turn at the extremity, and the triangular punched portions 
on the inside of the block, the position of these is exactly maintained. Fig. 3 



Mtii Caf/cecrr 



■Sscrfw or wall C^oum f^Loo/} Let^ec 
Fig. 4. 



108 



E 



constbuctjoma: 

£NGrNEERXNG 



1 



HOUSING SCHEME, HAYES. 



shows a piece of walling, while Fig. 4 is a section of the wall. The blocks are laid 
dry, but the use of the liquid concrete makes the whole into a monolithic mass. 
The clips on the outer face of the wall are cut off flush with the surface as the work 
proceeds. The aggregate for the blocks is klinker ; in this way a good fixing is 



a/^SS A . TYPE C. 



CLASS B. TYPE L 




Fig. 5. Plans. 
Hayes Housing Scheme. 



CROUNO rtOOR FIRST FLOOR 




llciiisos orcctcil with solid Concrete Walls ami riiiibor ShultiriiiK'- 
Hayes Housing Scheme. 



obtained for joinery. The outer surface is rough-castcd or cement rendered, or 
the outer blocks can be cast with a waterproof face ; furthermore, the porous 
aggregate prevents condensation. 

The actual method of procedure is to erect a soHd concrete Widl upon founda- 



log 



HOUSING SCHEME. HAYES. [QONCBETE ] 

tions to damp course level ; above this the cavity wall, filled in solid as the work 
proceeds, is built. To secure alignment wood profiles are erected at the corners of 




Fig. 7. Houses in course of erection on Fidler System. 
H.\YES Housi.vG Scheme. 




iMg. 8. General View of Site. 
Hayes Housing Scheme. 



the building. The slabs are then built to a line drawn from profile to profile. 
The cost of this method of walling is about 14s. per yard super ; the whole wall 
can be built by unskilled labour provided there be supervision at about the rate 



no 



i 



CONSTEUCnC 

EN GTNEEglNG ~-J 



HOUSING SCHEME, HAYES. 



of one bricklayer to four labourers. The system is extremely adaptable, and the 
houses need not be designed to any unit dimensions. Fig. 5 shows various t}^es 
of plans in use. In Fig. 6 are seen some houses in process of erection on the 
Fidler system. Fig. 8 gives a general impression of the site. The houses on 
the right are of the earlier type, erected with wooden shuttering. Fig. 7 gives a 
nearer view of the same type of house. At the present time there are some 800 
houses in course of erection, while 52 are completed ; the work in connection 
with the sewers is also finished. An interesting aspect of the scheme is the use 
of mechanical contrivances for economizing in labour. Fig. 9 shows the Bucyrus 
Trench excavator, which was used on most of the sewer cuttings. Much of the 
ballast was obtained by means of the Bucyrus Drag Line Excavator, and on the 
Dorman Long houses use was made of the cement gun. Materials are brought 
to the site in trucks running on a narrow gauge railway, drawn by petrol engines. 
The Fidler system is operated by The Composite Concrete Construction Co., 
of II, Duke Street, St. James', which has been formed for the purpose. Mr. 
Fidler is himself responsible for the Hayes scheme. Mr. J. M. Wilson is resident 
Architect, and Mr. James Donaldson resident Accountant. The Contractors 
are Messrs. Sir Robert McAlpine & Sons, of 50, Pall Mall. 




Showing Bucyrus Trench i:,.\cavator at Work. 
Hayes Housing Scheme. 



MEMORANDUM. 

Inquiry into the High Cost of Building. — Dr. Addison has appointetla Committee 
to inquire and report as to the reasons for the present high cost of building working- 
class dwellings and to make recommendations as to any practicable measures for 
reducing the cost. Mr. T. H. Sheepshanks of the Ministry of Health will act as 
Secretary to the Committee, and communications should be addressed to him at the 
Ministry of Health, Whitehall, S.W.i. 



H. J. BIRNSTINGL. lOQNCRETE] 

THE TREATMENT OF SMALL CONCRETE HOUSES, 

By H. J. BIRNSTINGL, A.R.I.B.A, 

{Continued from page 34. January.) 

The suitability of a building to its environment often becomes a matter of impor- 
tance in designing a monolithic concrete house, because monolithic construction, 
more than any other form of concrete building, provides scope for special treat- 
ment. And in certain parts of the country, where the very ground, the trees, 
and the buildings seem to exude a spirit of slowly changing traditions, so that 
in contemplating the landscape an atmosphere of romantic and historical associa- 
tions is created, it would be a veritable error of taste to erect a building whose 
form would be altogether inharmonious by reason of its novelty. In other 
districts, however, where this spirit of gentle maturity is not so manifest, a new 
architectural form might well afford no harsh contrast. 

England, in common with other countries of the North, is pre-eminently a land 
of pitched roofs. The reasons for the prevalence of this form of covering are too 
well known to require comment. The pitched roof carries off the rain and the 
snow with greater speed than would a flat roof. Moreover, there is a difficulty in 
constructing a flat roof that shall be weather-proof without resorting to the employ- 
ment of expensive materials. Concrete, however, not only provides a flat roof 
that can withstand rain and snow, but it is more suitably employed as a roof 
covering in this form than in any other (with the possible exception of the vault 
or dome), hence, it is not surprising to find that, in many instances, monolithic 
houses — and indeed concrete houses whose walls are built in other methods — have 
fiat roofs. It is an easy matter to foresee the kind of surrounding that would be 
most suitable to the flat roof. In towns it is no rare thing to find that the roofs of 
many quite small houses are invisible where they are hid behind a blocking course ; 
again, among pine woods or perhaps by the sea-shore, where the main lines of the 
landscape are horizontal, the flat-roofed house would not offend by contrast. 

In the monolithic house the item of expense is the shuttering, and it will be 
difficult to provide any complexities and irregularities of outline, or any profusion 
of ornament. The charm of the design will depend upon bold simple lines ; for 
the most part the horizontal will be emphasized rather than the vertical. Balance 
in the design will depend upon well-spaced and well-proportioned fenestration. 
The misplacing of a string-course is sufficient to spoil a simple wall by dividing 
the surface into ill-proportioned parts. The angles of a monolithic house can 
receive special emphasis at but little additional expense. Cornices will be simple 
with only a few members, but these must be carefully detailed. A concrete 
bungalow erected at Los Angeles, California, is illustrated irvFig. i. There is a 
certain charm in the boldness and directness of this design that is extremely 
satisfactory. The lines are simple, 3^et sufficient. There is no attempt to disguise 
the material, or the method of using it. At the first fulgurant glance the design 
may shock, but it does so only because it contravenes the accepted traditional 
forms. In matters of architecture there is a fundamental tendency to admire 
those things which most nearly approximate to the expectations of the individual 
beholder. It is difficult to view a building dispassionately, because architecture, 
more than any other art, is intimately bound up with human life. But progress 

112 



3, Cr/NSTBUCTIONA 
^ ENGIMEERING 



1 



TREATMENT OF SMALL COX CRETE HOUSES. 



can only be achieved by means of courageous experiments, and associations 
must not be allowed to hamper abstract judgments. 

A somewhat larger monolithic house is shown in Fig. 2. Here again the 
conspicuous feature is the simple massing. The interest in the design lies in the 
contrasts of light and shade. It is no exaggeration to say that in this building 
there exists a very real relationship between the design and the method of con- 
struction. There are no complexities of angles and differences in levels. The 




Fig. I. Concrete Bungalow at Los Angkles, California. 




iiiiiK CoNCKi-ii'; Ki siDiNci:, Chicago. 



shuttering would be of the simplest, and tlie work would progress in level horizon- 
tal courses. The actual system employed on this house is that known as the 
I'dlgren, which comprises a framework of grooved studding, to which the inner 
shuttering is attached. This studding is partly embedded in the concrete and partl>' 
projects, and to it the inner lining of lath and plaster is subsequently fixed. In this 
way the cavitv is formed. It will be seen, then, from these two examples, that 
without straining for logical results, or the vindication of any abstract theories on 
design, the system of monolithic construction has its own definite characteristics. 

E ' 113 



H. J. BIRNSTINGL. 



[C DNCRETEJ 



In Fig. 3, however, is seen a monolithic house that breaks but Uttle new ground. 
Concrete being unsuitable for fine detail work such as can only be achieved 
by the skill of the joiner or the mason, the cornice and doorway are in wood. 
There is ample enough precedent for the combination of brick and timber in 
17th and 18th century work, and concrete and timber may well be combined for 
a similar reason. The unornamented chimney stacks show again that an en- 
deavour would appear to have been made to simplify the shuttering to the utmost. 
This house is erected in America and is based on the " Colonial " tradition. 

The Mansard roof has never found favour in England. It is difficult to account 
for the persistence of this prejudice, since as a roof form it has both economy 
and charm to recommend it. In France, Belgium, Germany, and Holland, it is 




Fig. 3. Monolithic House in America. 



employed extensively. Fig. 4 shows a monolithic concrete house with a Mansard 
roof. The main form of the house is kept simple and direct, the front wall is 
carried up to form the face of the dormers, nevertheless, although the design is 
delightful in itself, it does not emphasise the particular quality of the material in 
which it is built. 

The " gunite " house consists of a timber frame, a backing of Willesden 
canvas or some similar material, expanded metal lathing, and a covering of 
concrete applied under pressure by means of a cement gun. It will at once be 
appreciated that this system is therefore only suited to small buildings. The same 
necessity for simplicity in outline will not exist as maintains with the employment 
of shuttering. There is no inherent difficulty, and no great expense in framing or 
covering a building which may possess somewhat complex gable ends and dormers, 
so that it is legitimate to expect a more picturesque effect, due to a greater diversity 

114 



l 



CONSTRVCnaNA 



1 



TREATMENT OF SMALL COUNTRY HOUSES. 



of plane surfaces. Fig. 5 shows a small house built of timber covered with building 
paper, metal lathing, and concrete : actually this house is built around an old 
timber cottage which formed the nucleus for the larger building that is illustrated. 
Particularly characteristic of such materials is the treatment of the buttresses. 




Fig. .). Mio.i.iriim; Concrete House im America. 




I'll.. 5. CoNCRITE lloi'SE AT VoUNl.STOWN. 

By no other means would it be possilile to form the Ixittered surface with so little 
additional expense. This design, tlien, may be takcMi as an indication of the kind 
of treatment to which the material and the method of using it most easily adapts 
Itself. 

Ihere is one important aspect of the subject to which, so far, but scant 



K2 



115 



//. ]. BIRNSTINGL. 



(CDNCKETE J 



reference has been made. Texture and colour are as important considerations 
in concrete as in brick or stone, and, as in these materials, their quality will, for 
the most part, be governed by cost. In America the process known as aggregate 




Fllj. 6. ExAMFLtS OF Aggrlgate HxI'OSI.N 



exposing has been successfully developed. Various methods are used, such as 
scrubbing, brushing, or washing with dilute muriatic acid. The aggregates are 
very carefully selected and graded so that the desired colour may be obtained. 



Ii6 



1' 



1 



y 




! 






House at Welwvn Garden Civ on the " C.D.L." System. 
(for description see page ii8.) 



^gSoi^^i^ TREATMENT OF SMALL CONCRETE HOUSES. 



Fig. 6 shows two examples of aggregate exposing. It would seem that there is a 
distinct opening for experimental work in England in connection with concrete 
surfaces. The usual practice seems to be, either to cement render or to rough cast 
where a protective coat is applied ; a little enterprise might reveal other surface 
treatments that might not add materially to the cost of the building. 

The various methods of construction, and the treatment which they suggest, 
can now, perhaps, be summarised. The block may be used in the same way as 
a poor qualit}' brick ; when it is so used the question of scale is of no importance, 
attempts should be made where circumstances permit to devise some more 
interesting protective coat than the ubiquitous rough cast. WTiere the block 
is not faced, care must be taken that it is not out of scale with the building. Here, 
too, a more interesting surface might well be obtained than that which is usuallv 
encountered. This will to some extent depend upon the aggregate and the method 
of employing it. The steel-framed house has very definite limitations, since the 
parts must be standardised and the outline kept as simple as possible. The 
monolithic house is probably the cheapest to erect where aggregate is obtainable 
on the site. The designer must always be mindful of the shuttering ; he will 
therefore attempt to obtain his effects by large masses of voids and solids, and 
light and shade. The main lines will, for the most part, be horizontal ; he must 
give particular consideration to the environment of his building. The flat roof 
should only be used with the greatest discrimination. With the gunite house 
there exist fewer restrictions of form and outlme. There is considerable scope 
for buttressing and arching, for irregularity of outline, and it is possible to indulge 
in greater complications of surfaces. It might be said that the gimite house 
can be picturesque rather than dignified, although it should be remembered that 
picturesqueness is not in itself an architectural qualitj'. 

If, however, the best results are to be obtained from concrete, it is essential 
that architects, who are alive to the problems of the day, to its aspirations and its 
requirements, should interest themselves in the material. Without doubt many 
of the recently erected concrete dwellings are unsatisfactory because they are 
the work of micn who are interested in concrete as a material, but who lack the 
necessary qualifications and training to enable them to produce a successful 
design. It is but to be expected that the architect should be able to appreciate 
the aesthetic possibilities of the material, which are indeed very real, and he will 
perhaps best achieve this by collaboration with those who have had actual first- 
hand experience with the material. Such a partnership should produce the good 
results which it is known can be obtained from concrete, but which are, neverthe- 
less, so often lacking in contemporary work in England. 

MEMORANDUM. 

Birmingham Architectural Association. — At the fifth general meeting of the 
Birmin^^'liani An liitin tiiral Association, Professor F. C. Lea read a paper entitled 
Reinforced Concrete," in whicli he said we were living in an age when labour and 
material were expensive, and one of the problems of tlic day was how to maintain 
economy of expenditure in buildings, not only with the highest degree of suitability 
to tlie particular purpose for whicli tliey were to be used, but also to obtain the best 
and most pleasing architectural effects. Reinforced concrete could no doubt be used 
to satisfy those aims, and architects, working with tiiosc who understood the con- 
structive and .scientific possibilities of tliis material, might use it to produce worthy 
.structures. 



THE "C.D.L." SYSTEM OF CONSTRUCTION. 



[CQNCBETEJ 




Fig. 3. 



This \'ie\v shows the Raft of a " L.U.L." riousi;, with 

SECOND COURSE IS SEEN ON THE LFFT-HAN 



i lIKal COURSE OF THE WALLS. 
SIDE OF THE PICTURE. 



.•\ PART OF THE 



THE *' C,D,L/' SYSTEM OF CONCRETE 
CONSTRUCTION. 

By the courtesy of Concrete Dwellings (Parent Compan}') Limited, of West- 
minster, we have been allowed to watch the operation of their " C.D.L." machine 
in the actual construction of dwelling-houses at Dailymail, a portion of the 
Welwj^n Garden City Scheme. 

Under this system of house-building, soHd walls, or hollow walls with 
concrete ties, are constructed by means of a travelling mould shown in Fig. 2. 
If a hollow wall is to be built the mould is provided \\dth a core ; if a solid 
wall is desired, the core is absent. 

In the case of the hoUow wall, in order to form the concrete tie a piece is 
cut out of the core which is shaped as in the sketch Fig. i. The result is that 
the concrete which fills the space so formed extends across the cavity and con- 
stitutes the tie which is monolithic with 
the inner and outer leaves of the w^all. 

If desired, cavity walls ^vith metal 
ties can also be constructed with this 
machine. 

Foundation. — The method of con- 
struction is as follows : The footing to 
the walls is made in the usual way and, 
following accepted practice, is double the 
width of the walls themselves. The upper 
surface of the footing is left rough in order to provide a ke}^ for the first course. 
Inside the footing a concrete raft, 6 in. thick, is laid in situ over the whole 
site. This is shown in Fig. 3. 





\ 


\ 






\ 




N 


L 





118 



K 



CDNSTKUCTIOTMA 
EI»iGrNEERING 



3 



THE "C.D.L." SYSTEM OF COXSTRUCTION. 




Illustrating the Method of Constructing a Cavity \Vall \\nTH the " C.D.L." M.'^chine. 



The Walls. — The thickness suggested for cavity walls is 9 in., made up of 
two leaves each 3J in. with a 2^ in. cavity between. 

The mould is placed in position on the footing which has been previously 
marked out with builder's lines. It is then gradually filled with a semi-dry 
mixture, which is rammed continuously. During the ramming the sides and 
core are automatically held in position. As soon as the mould is full and the 
upper surface of the material trimmed, the sides are released by means of a 
patent expanding and contracting mechanism, and a well-rammed, semi-dry 
mixture having been used, the machine can then be moved forward, leaving 




Fig. 4. "C.D.L." Houses under Construction, showing iiii. \\ all^ vi- I'j J iicsi 1-loor Le\t;l. 

119 



THE "C.D.L." SYSTEM OF CONSTRUCTION. 



(OQNCBETEJ 



O 



>- 



< 




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< 



o 



o 



Is. 



1 " 

4. 





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O 

I 

LU 



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CONSTCUCnONAL 
ENGTNEERING ^-. 



THE "C.D.L." SYSTEM OF CONSTRUCTION 




THE " C.D.L." SYSTEM OF CONSTRUCTION. 



[CDNCRETEJ 



behind it a section of wall the size of the mould. This process is repeated until 
the first course of all the walls is complete. 

After twenty-four hours the machine may be placed on the top of the pre- 
viously constructed work, which is well wetted and the next course laid. Thus, 
course by course, the wall is erected and forms a monolithic structure. The walls 
up to first floor level are seen in Fig. 4. 

The moulding of the corners is an interesting operation. The corner of each 
course is formed by an L-shaped attachment, similar in other respects to the machine 
itself. This is first placed in position. Two machines are then attached, one at 
the end of each arm of the corner-piece. (In certain circumstances, one machine 
only is attached.) The corner is thus formed monolithically and without joint. 

In order to ensure that the walls shall be absolutely plumb, the position of 
the mould is corrected for every section by means of a spirit level, it being obvious 
that if correct horizontally, the course will be correct vertically. 




If desired, different materials may be used for each leaf of a cavity wall, so 
that, say, gravel concrete may be employed for the outer leaf, and concrete having 
a porous aggregate for the inner, in order to overcome the condensation difficulty. 

The partition walls are built on the same principle except that they are solid 
and 4l in. thick. 

Into the sides of doorways and window-openings strips of wood are cast in 
order to make provision for affixing the woodwork, and pre-cast reinforced con- 
crete lintels are employed over doorways and window openings. 

Damp-Course. — For the damp-course, the provision of which is always 
advisable, any recognised material may be employed. 



E 



CX)NSTPUCT10NAL1 



THE "CDL." SYSTEM OF CONSTRUCTION. 



Roof. — In the case of the houses being erected on this system at Welwyn 
the roof is to consist of two layers of pre-cast concrete slabs arranged with a 
cavity between them, and the joists also will be of reinforced concrete. 

Material. — Local gravel, excavated on the site, is employed as the aggre- 
gate. This is screened and re-mixed in the proportion of i ; 2 : 4, the coarse 
material not exceeding f in. in diameter. 

Surface Treatment.- — It is proposed to rough-cast the walls externally and 
coat them internally with lime plaster. 

General. — This system, like many other concrete systems, will provide 
another avenue for the employment of ex-service men. On the two houses being 
erected at Welwyn, all the men employed except the foreman are unskilled. 

The Company do not propose to undertake concrete work themselves, the 
intention being to work on licence through builders and contractors. Any builder 
who adopts this system will be supplied by the Company with a trained man 
who will instruct the builder's own workmen. 

The system, which has been approved by the Ministry of Health, is patented 
in all countries, and actual work is being carried out in France, Italy, Belgium 
and India in addition to the United Kingdom. 

The specific claims made for this system are : No expensive machines 
necessary. No previous moulding of blocks. No storage. No multiple hand- 
ling. No block-setting. No grouting, since everything is done in one operation, 
and, since one course is laid daily, rapidity of construction is ensured. 

In the case of one house, nine men working seven hours a day erected the 
walls up to roof level in ten days. 

The Architect for the Welwyn Garden City scheme is ]\Ir. Louis de Soissons, 
A.R.I.B.A. At the time of going to press these houses^were unfinished, but the 
artistic appearance which it is anticipated they will present is indicated by the 
drawings which are reproduced in the frontispiece and in Fig. 5. Figs. 6 and 
7 are photographs of two other houses erected on the " C.D.L." system. 




CONCRETE ROADS FOR WORKS AND FACTORIES. I CONCPFTF ; 




CONCRETE ROADS 

FOR WORKS AND 

FACTORIES. 



n 



It is fast becoming a recognised fact that concrete forms an ideal road surface for 
the many roads and driveways leading to large works and factories, in view of the 
heavy and continued traffic passing ov^er them, and in the last few years a large 
number of our industrial firms have adopted concrete for this purpose. 

In the United States this form of construction has been even more widely 
used, but an interesting development in this direction is the adoption of such 
roads for the large oil refineries and distributing stations in America. In this 
instance owners had to consider the effect on the concrete of the oil drippings 
which it was feared might make the roads slippery and perhaps cause deterioration 
of the concrete. Experience has, however, shown that these fears were groundless, 
and our readers may be interested in the following particulars and illustrations 
taken from the Concrete Highway Magazine, giving a short account of what has 
been the experience of some of the American Oil Companies. 

" At many oil refineries and retail and wholesale oil distributing stations, the 
common drivewa}^ and teamyard paving problems are being successfully solved by 
the use of concrete. The service required of concrete pavements by the oil 
industry is somewhat more exacting than in many other lines of manufacture. 
The traffic loads are frequently excessive and the surface must be able to resist 
the action of oil drippings without becoming slipper}^ 

" The general practice in the design and construction of concrete pavements 
for driveways of this character has followed somewhat closeh' the developments of 
concrete highway pavement construction. In the early stages of the expansion 
of the oil industry and before the adoption of motorised distributing units it was 
often thought sufficient to lay a surface of oil or asphalt-bound macadam or gravel. 
This type of surfacing was soon found inadequate for the requirements, and so the 
construction engineers of this industry turned to concrete. 

"Their first concrete driveways were not always successful, because it was 
thought the design and methods of ordinary concrete sidewalk construction would 
be ample. However, with the increase in weight of motorised tank trucks it was 
soon found that the principles of standard concrete pavement construction must 
be followed. Present specifications for concrete driveways used by the oil industry 
follow closely the recognised features of the best highway construction as to 
thickness, reinforcement, mixtures, cleanness of materials, and finishing and curing 
methods. 

"The surface finish and wearing qualities of concrete pavements at retail 
gasoline stations are especially important. It is necessary to produce a surface 



124 



i 



CONSTRUCTIONAL^ 
EMOIMIXRING —J 



CONCRETE ROADS FOR WORKS AND FACTORIES- 




1-25 



CONCRETE ROADS FOR WORKS AND FACTORIES. [CDMCBETE] 

which can be quickly cleaned by flushing with a hose-stream and from which the 
snow can be easily shovelled in winter. The attendants at these stations cannot 
allow snow to accumulate, but must clean it away frequently during the course of 
a storm. This makes it important that the surface offer minimum resistance to 
shovelling or sweeping. The surface must be sloped on true lines so that water 
will drain away quickly. To meet these requirements the surface is usually 
trowelled more carefully than is the case on street or road pavements. 

"The typical oil plant or refinery is marked by neat buildings, well-arranged 
yards, and concrete pavements. An interesting example is found at the Long 
Island City, N.Y., plant of the Texas Co., which produces the " Texaco " line of 
petroleums and asphalts. At this plant some 3,900 square yards of concrete 
pavements have been completed. 

"The Standard Oil Co. of New Jersey has nearly 30,000 square yards of 
concrete drives at three stations in Massachusetts and Rhode Island. 

" Many retail stations of the various Standard Oil Companies scattered from 
coast to coast are distinguished for convenience and appearance because of the 
excellent concrete pavements which have been provided. Among other firms 
which are rapidly improving wholesale and retail distribution plants with concrete 
are the Union Oil Co. of California, the Shell Oil Co., the Pure Oil Co., the Con- 
tinental Oil Co., and the Sinclair Refining Co. 

" The accompanying illustrations show how concrete pavements serve the oil 
industrv from coast to coast." 



MEMORANDUM. 

A New Stretch of Concrete Highway in British Columbia. — Towards the end 
of December a length of concrete road, which is to form part of the Great Pacific 
Highway from Vancouver to Mexico, was thrown open to traffic. The work had been 
carried out by the Ministry of PubHc Works. Victoria. This particular stretch brings 
the junction of the Yale and Johnston Roads within an easy distance of the Royal 
City Post Office. 

At the opening ceremony, emphasis was laid upon completing the road as far 
as Blaine, so that Canada might be represented with a fully paved section of the 
great highway stretching from Vancouver to Mexico. 

Mr. Foreman, President of the Canadian Good Roads Association, and formerly 
engineer of the Public Works Department at Victoria, stated that as a section of the 
Transprovincial Highway, as well as of the Pacific Highway, the road just declared 
opened was destined to be a link in the great Dominion highway stretching from 
Halifax to the Pacific coast, which the Canadian Good Roads Association was devoting 
its energies to promote. It was announced that an early start would be made on 
the last remaining important link in the Transprovincial Highway, i.e. from Hope to 
the system of roads in the dry belt. 

Those inspecting the length of road thrown open to traffic were impressed with 
the excellent quality of the pavement, which is of the same substantial type of concrete 
as British Columbia motorists are familiar with in stretches of the Pacific Highway 
in the State of Washington. 

The pavement is wide enough for two cars to pass abreast, and has a gravel fill 
extending on each side to a width of four feet. 

An awkward hill which existed on this stretch of road had been graded so effec- 
tively as to enable drivers now to take it with great ease. 

126 



A'g:?i^^SNS'^ REINFORCED CONCRETE SHIP CONSTRUCTION. 




RECENT VIEWS ON 
CONCRETE AND RE- 
INFORCED CONCRETE 
CONSTRUCTION. 



THE INSTITUTION OF 
CIVIL ENGINEERS 




*' REINFORCED CONCRETE FOR SHIP CONSTRUCTION." 

By Professor THOMAS BERTRAND ABELL, O.B.E., M.Eng. 

The following is a short abstract from a paper read before the above Institution 
on January ilth. 

The paper places on record particulars of tests on and the general experience gained 
with concrete and reinforced concrete used in the construction of concrete sea-going 
vessels designed and built under the direction, first of the Admiralty and, subsequently, 
of the Controller General of Merchant Shipbuilding during the years 1917 and 1918. 

Crushing tests carried out on the concrete with various types of aggregate are 
summarised. The concrete was of a rich mixture varying from one part of cement 
with 2-67 parts of mixed aggregate, to one part of cement with 3 66 parts of mixed 
aggregate. The aggregate consisted of natural gravel or crushed stone passing through 
|-inch square or J-inch round holes. The crushing tests show a wide variation in 
strength. It became clear there was no disadvantage in using a well-rounded smooth 
beach-gravel as aggregate. Better lesults were obtained with such an aggregate than 
with an angular aggregate. Good grading of the aggregate, together with extra fine 
grinding of the cement, were always found advantageous. 

Density of concrete is important for ship construction, since the weight of the ship 
without cargo is an important factor in determining the dimensions of the ship. The 
extreme variation in weight per cubic foot amounted to 10 lb., involving nearly 7 per 
cent, variation in the weight of the hull structure. 

Bending tests were conducted on reinforced concrete beams to determine 
(i) The value of concrete under tension ; 

(2) The comparative value of round bars and different types of wire rope for 

reinforcement ; 

(3) The behaviour of concrete under alternating stress : 

(a) At a stress less than that corresponding to rupture under tension ; 

(b) At a stress greater than that corresponding to rupture under tension. 
Particulars of the beams used and the curves of deflection and load are given. 
The beams for the alternating tests consisted of hollow cantilevers of rectangular 

cross section erected vertically. Their lower ends were fixed in the ground, and the 
upper ends were subjected to an alternating force having a frequency of 4 to 7 (complete 
reversals) per minute. The calculated stresses in the concrete during the experiments 
were 180 11). and 360 lb. per square inch. The cantilevers were filled with water so 
tiiat evidence would be forthcoming directly the concrete on the tension side was 
completely fractured. Cracks were produced after a time with the tensile stress as 
low as 180 lb. per square irrch. 

The notewortliy feature about the tests was the eventual sealing of cracks through 
which water iiad been percolating. Whctlier the sealing was due to furtiicr liydration 
of the cement after grinding under the alternate opening and closing of tiic crack was 
not determined, but tlie cracks remained tiglit and were onlv reopened on increasing 
the load. 

The total number of reversals was 200,000 on one beam and 100,000 on a second. 

Further tests were made to determine whether concrete could be placed on a 



127 



REINFORCED CONCRETE SHIP CONSTRUCTION. [C QNCBETE] 

practical scale in thin slabs so as to act as a container for heavy oil fuel f)f high flash- 
point, and also for petrol. There was no difiiculty in regard to the heavy oil, and 
though with extreme care concrete containers might have been made to retain petrol, 
it was decided that the risk would be far too great to enable petrol to be carried in 
bulk in a ship. 

The remaining tests relate to experiments carried out to determine the permea- 
bility of concrete, the means of protecting reinforced concrete from the corrosive action 
of salt water and from the disintegrating effect of vegetable lubricating-oils on the 
interiors of the self-propelled vessels. 

It was found that without any surface treatment 2-inch slabs of concrete, cast 
with their faces vertically, would frequently resist water pressure of 200 lb. per square 
inch. It was concluded that it* was unnecessary to use any water-proofing compound, 
and that the richress of the concrete, together with the grading of the aggregate, were 
sufficient to guarantee water tightness. 

The paper contains several diagrams and an appendix giving particulars of the 
tests. 

MEMORANDA. 

The South Wales Institute of Engineers. — An interesting paper was read before 
the above Institute on December lO last on the Application of Cementation to Mining. 
Owing to lack of space we have had to hold over an abstract from this paper until 
our March number. 

Shipbuilding. — A concrete motor vessel has been built at North Sydney, in Nova 
Scotia. It is 127 ft. in length, 27 ft. in beam, with a depth of 12J- ft., the net register 
being 282 tons. A 240 h.p. Bolinder oil engine is installed. This vessel is to be 
employed in the Sydnev-Newfoundland trade. 

A Finish to Concrete Floors. — In a recent issue of our contemporary, Concrete , 
U.S.A., it is stated that in a number of concrete houses that are being built all the 
floors are concrete, and in order to overcome the objection usually made to concrete 
floors in dwelling-houses, these floors were brushed over with common brown creosote 
stain, and when this was dry they were given a generous application of floor- wax. 
This was rubbed and the floors have a smooth wax finish, and give an appearance of 
warmth. They are easily kept clean. 

A Floor Test. — In view of the article published in another part of this issue dealing 
with the flat slab system of construction, it is interesting to note a test on a floor 
built on this system recently at the Garston Match Factory, Liverpool, for Messrs. 
Maguire, Paterson & Palmer, Ltd. The spans between the cclumns are 20 ft. and 
the diameter of the columns is 20 in. The floor was designed to carry 3 cwt. per ft. 
super and was submitted to a test load of 4 cwt. per ft. super. 

The Architects for the building are Messrs. Me wes & Davis, the reinforced concrete 
was designed by Mr. S. Bylander, and the constructional work was executed by Messrs. 
F. D. Huntingdon, Ltd. 

Reinforced Concrete Design. — In a recent lecture before the Department of Engin- 
eering, Johns Hopkins University, Baltimore, Mr. Ernest P. Goodrich, of New York City, 
said that thus far throughout the history of reinforced concrete the general tendency 
had been to force that material into forms both structural and architectural which 
were like those to which engineers and architects and the general public had hereto- 
fore been accustomed, such as timber beams and columns, stone quoins, lintels and 
sills. Obviously, however, reinforced concrete was inherently different from those 
materials, and the highest art should and would doubtless eventually develop designs 
for structures and fa9ades which belonged as intimately to reinforced concrete as 
did the forms above mentioned to structures now made of separate members. In 
spite of the rapid advancement which had been made in the last decade in the field 
of use of reinforced concrete, and the designs of structures employing it, it was 
believed that the possibilities of the field had not begun to be exhausted, nor had the 
end been reached in the devising of improved methods for the handling of materials, 
the manufacture, erection and rehandling of forms, the surface treatment of exposed 
work or the reductions in cost which might be effected by saving material through 
more detailed studies of secondary stresses and the methods of best providing them. 

128 



1 



CONSTRUtTlONALl 
ENOIMEERING - 



CO^XRETE IN THEORY AND PRACTICE. 



JaEI 

CONCRETE IN THEORY 
AND PRACTICE. 

A practical section especiaUy written for the assistance of students 
and engineers, and others who are taking up the study of reinforced con- 
crete, or icho are interested in the subject on its educative side. 

REINFORCED CONCRETE SIMPLY EXPLAINED. 

By OSCAR FABER, O.B.E., D.Sc, etc. ' 

In this series of articles it is proposed to keep explanations so simple as to he 
intelligible to anyone desiring to understand the underlying principles of reinforced 
concrete without wading through a lot of mathematics. The results will be accurate 
and will agree with L.C.C. regulations, hut will be more easy to understand. The 
articles should also form an excellent introduction to those who will need to folloiv 
them up with a more advanced work. — Ed. 



CHAPTER V. 

Design of Columns. 

69. It has already been explained how 
columns may be designed to carry definite 
loads centrally or axially applied. 

It has also been explained that in 
practice it is practically impossible to 
secure axial loading. Perhaps the reason 
for this is worth recapitulating. When 
a beam is built monolithic with a column 
at each end, and loaded, it necessarily 
deflects, so that the end now takes up a 
slope if it were originally horizontal. 
The effect is that either the beam rests 
on the inside edge of the column, or else 
the column bends so that its upper end 
takes up the same slope as the end of 
the beam. In either case, the column 
is subjected to a bending moment in 
addition to the direct load. 

Now the amount of the bending 
moment depends on the relative stiffness 
of the beam and the column. 

If the column is very stiff compared 
to the beam, it will offer great restraint 
to the end of the beam, and will approxi- 
mate to the case of a beam fixed in direc- 
tion at the ends, for which the bending 

. Wl 
moment is at the ends. 

12 

If the column is very flexible compared 
to the beam, it will offer very little res- 
traint, and the bending moment at the 
joint will approximate to zero. Prac- 
tical cases lie between these limits. 

Now a convenient measure of tlie 
relative stiffness of column to beam is 

KG 

the quantity .. which may be written — 

A' = a constant depending on tlie 
fixity at the lower end 01 tlic column, and 
niav be taken as 6 for outside columns 
and .( for iuttMior columns. 



C = the moment of inertia of the 
column divided by its length. 

B = the moment of inertia of the beam 
divided by its length. 

TABLE I. 

Properties of Standard Square 
Columns. 







Equiva- 


Moment 








lent 


of 


Radius 


Size. 


Vertical 
Rods. 


Area. 


Inertia. 


of G^Ta- 




Concrete 


Concrete 


tion. 






Units. 


Units. 





In. 


Diam. 


Square 
In. 


In.* 


In. 


6X6 


4—^ in. 


47 


119 


1-58 


8X8 


4— i „ 


75 


385 


2-26 


10 X 10 


4-f „ 


117 


992 


2-91 


12 X 12 


4-f „ 


169 


2,135 


3-56 


14 X 14 


4-1 „ 


230 


3,940 


4-14 


16 X 16 


4—1 „ 


300 


7,090 


4-86 


i8 X 18 


8-J „ 


373 


10,510 


5-3 


20 X 20 


8-1 „ 


467 


16,540 


5-94 


22 X 22 


8—1 „ 


572 


24,920 


6-59 


24 X 24 


8—1 „ 


664 


34,000 


/•14 



Note. — This table does not allow for neglecting 
1 J in. of cover, as suggested in L.C.C. regulations. 

Now in the table in par. 50 the moment 
of inertia of the author's series of standard 
beams was given. 

In Table I. it is also given for the 
author's standard square columns. 

With these tables before us, it is there- 

KC ^ 
fore quite easy to calculate r. for any 

given case. 

Suppose, for example, we have a beam 
25 ft. span carrying 25,000 lb. distributed 
load, supported on columns 12 ft. o in. 
long in tiic upper storey. 

We shall find that our standard T beam 
20 in. X 8 in. will be required, as 
explained in DiajitiT III. and our table 



129 



CONCRETE IN THEORY AND PRACTICE. 



[CDNCRETEJ 



gives the moment of inertia of this beam 
as 10,300, whence 

10,300 

B = ^— = 3,433, 

300 m. j'-tj-j' 

300 being the length in inches (25 feet). 

Suppose we support this on columns 

16 in. X 16 in., we find from Table I. that 

the moment of inertia is 7,090, whence 

7,090 

C = = 4,700, 

150 ^" 

150 being the length in inches (12 ft. 6 in.). 

Taking /C as 6 for outside columns, we 

have 

KG 6 X 4,700 „ 

-^— = 3-^ — = 8-2. 

B 3>433 

TABLE II. 
Bending Moments in Outside Columns. 



TABLE III. 
BendingMoments in InteriorColumns. 



KC 
B 



Bending Moment. 



Wl 





333 




Wl 


- 


174 




Wl 


•5 


76-5 




Wl 


I-O 


42-7 




Wl 




27-5 




Wl 


5 


18 




Wl 


10 







14-9 




Wl 


20 


13-3 




Wl 


30 


12-8 




Wl 


00 


12 








•003 


Wl 


•0057 


Wl 


•0131 


Wl 


•0234 


Wl 


•0365 


Wl 


•055 


Wl 


•067 


Wl 


•075 


Wl 


•078 


Wl 


•083 


Wl 



Note. — For outside columns A' = 6 generally. 

Tables II. and III. give the bending 

moments in the column for various ratios 

KC 
of "B", and from Table 1. it will be seen 

that the bending moment corresponding 

KC Wl . , . 

to —f^ = 8'2 is about rz , which in our 



B 

case is 



16 



25,000 lb. X 300 in. 

16 
470,000 in. lb. 



KC \, 
B 



Bending Moment. 







Wl 





•I 


480 
Wl , 


•00208 Wl 


~ 


250 

Wl 


•004 Wl 


•5 


117 

Wl 


•00933 Wl 


I-O 


60 

Wl 


•0167 Wl 


2 


36 

Wl 


•0278 Wl 






5 


21-6 

Wl 


•0462 H'/ 


10 


i6-8 
Wl 


•0595 Wl 


20 


14-5 
Wl 


•069 Wl 


30 


13-8 
Wl 


•0725 \M 


00 


12 


•083 Wl 



Note. — For interior columns A" = 4 generally. 

The stress in the column due to bending 
is given by 

My 
~I 
where M is the moment, 

y is half the thickness of column, 
/ is the moment of inertia, 
or, in our case, 

470,000 X 8 in. 



= 530 Ib./in.' 



4ii 



7,090 

The direct stress due to 
the load is 

12,500 _ 

300 

Total 57 1 J 

300 in the above calculation being the 
equivalent area of the concrete, as given 
in Table I. 

There are good reasons for thinking 
that when the stress is calculated in tliis 
way much higher figures than 600 
Ib./in.^ are justified, though in the 
example given we have kept them under 
this figure. 

{To be continued.) 



130 



E 



CONSTCUCnCW, 
EIVGrNEERING 



g 



CEMENT NOTES. 



CEMENT NOTES. 



By Our Special 
Storage of Cement. 

In the July issue of this Journal a 
summary was given of a report from the 
Structural Materials Laboratory of Chi- 
cago, upon the effect of storage of cement, 
the concluding paragraph of which stated 
that there is reason to believe that cement 
may be stored in bulk for long periods 
without materially affecting its concrete 
and mortar making qualities. Some- 
tests that were recently made in this 
country give a striking support to this 
belief. 

A consignment of about 300 tons of 
cement was stored in bulk in a shed on 
the East coast for three years and when 
examined at the end of that period it 
was found that a crust about 3 in. in 
thickness had formed upon the surface ; 
when this crust was removed, the re- 
mainder of the cement was found to be 
of excellent quality as shown by the 
following tests : — 

Residue on 180 sieve . 11 '5 % 

Initial Set 85 minutes 

Final Set 283 

Le Chatelier Test . . nil 
Tensile Strength — 7 daj-s neat 688 lb. 
per sq. in. 

Tensile Strength — 7 days 3 sand i 
cement — 280 lb. per sq. in. 

These results suggest that if at any 
time it is impossible to avoid the storage 
of cement, it is far better to store it in 
bulk than to attempt to keep it in sacks. 

The Value of the Brand in the Portland 
Cement Industry. 

In the latter half of the nineteenth cen- 
tury, the distinctions between the various 
brands of Portland Cement were more 
marked than they are in these days of 
standard specifications, and the practice 
of specifying certain brands was some- 
what widely adopted by engineers and 
arcliitects. 

There were good reasons for this prac- 
tice because the manufacture of cement 
was practically in its infancy and the 
differences in cjuality between one brand 
and another were appreciable. 

The reputations for reliable quality 
established by certain manufacturers 
last century arc still effective at tiic 
present day, and, on tlio other Iiand, the 



Contributor. 

prejudice against cement made in certain 
districts — arising from attempts to pro- 
duce cement with inadequate plant — 
has not yet died out, although there now 
remains no justification whatever for 
such prejudice. 

It is undeniable, however, that strong 
preferences and strong antipathies in 
connection with certain brands of Port- 
land Cement still exist, and a considera- 
tion of the causes for these may be 
enlightening. 

It may be taken for granted that all 
Portland Cement produced in this coun- 
try complies with the British Standard 
Specification, and the popularity enjo^-ed 
by some brands of cement must be due 
either to superlative quality as judged 
by British Standard Specification tests 
or to some other cause not revealed by 
such tests. 

Firstly, with regard to the standard 
tests, it is evident that the quality appeal- 
ing to users would be tensile strength 
above the average, resulting in a corre- 
spondingly stronger concrete. Fineness 
of grinding has no intrinsic value in itself, 
but is merely a means of obtaining 
additional strength, although to a con- 
tractor who buvs cement bv weight and 
uses it by measure, the extra bulk of 
finely ground cement is an attraction 
from a commercial standpoint. A cement 
therefore that consistently shows tensile 
strengths of 800 lb. when neat and 350 
lb. when mixed with three parts of sand 
and tested at seven days would cer- 
tainly be preferred to one that yielded 
say 500 lb. and 220 lb. respectively 
under the same conditions. Hence, the 
cement manufacturer has one very 
obvious method of improving the reputa- 
tion of his brand by improving his tensile 
tests. By what means this cat) be done 
is not within the scope of this article to 
discuss. 

Specification tests do not, however, 
reveal the secret of the popularity enjoyed 
by some brands because the popularity 
depends upon the faculty of rapid harden- 
ing, and it should here be explained that 
(juick setting and rapid hardening are 
terms which when used in connection 
with Portland Cement have different 
meanings. 

131 



CEMENT NOTES. 



[CDNCBETE] 



A " quick-setting " cement is one which 
reaches a certain arbitrary standard of 
consistency in less than thirty minutes, 
and the term has no reference whatev'er 
to the hardness attained in twelve or 
twenty-four hours. The term " rapid 
hardening " refers to the behaviour of 
the cement in the period immediately 
following the final set. 

It is not uncommon to find that a 
cement with a final set of fovir hours is 
harder at twenty-four hours than one 
with a final set of twenty minutes, while 
at seven days the tensile strengths of the 
respective cements may be equal. 

The quality of rapid hardening is 
particularly acceptable to the cement 
user — it enables him to proceed with his 
work at high speed because in eighteen 
or twenty-four hours his concrete is 
strong enough to bear the weight of 
superincumbent material — it reduces the 
amount of shuttering required, and it 
produces a concrete or mortar that is 
less liable to damage by frost, sun and 
wind. 

Tests for rapid hardening are indeed 
the only tests applied to cement by the 
" man in the street " or his technical 
relative, the navvy, and a concrete that 
will bear his weight " the next morning " 
earns his commendation and stamps the 
cement in his mind as satisfactory. 

Many manufacturers are entirely in- 
debted to Nature for this desirable 
feature of their cement, because it is due 
to certain characteristics of the raw 
materials used in its manufacture, but 
there is hope that scientific research may 
be able to point the way to a general 
improvement in this respect which wall 
be applicable to all cements. 

The conclusion is thus reached that 
although the British Standard Specifica- 
tion has been instrumental in levelling 
up the quality of cement produced 
throughout the United Kingdom, there 
is still justification for preferences in 
connection with brands of Portland 
Cement. 

So far as the export trade in cement is 
concerned, the brand is of great import- 
ance. In many countries there is no 
standard specification and facilities for 
cement testing are almost non-existent, 
so that the cement user has only the 
brand to guide him as to the quality of 
the material he buys. It is in such cases 
as these that the reputations for good 

?32 



quality established by some manufac- 
turers last century and steadily main- 
tained since, have been of benefit not 
only to the manufacturer but also to 
the user abroad. 

Doubtful Aggregates. 

There are certain materials which, 
considered as concrete aggregates, must 
be classed as doubtful, becau.se although 
they may yield excellent results in nine- 
teen cases out of twenty, or even ninety- 
nine cases out of a hundred, there occur 
instances here and there of failures 
'which never happen when broken stone 
or clean gravel are used. Such doubtful 
aggregates are Blast Furnace Slag, Coke 
Breeze, Destructor Refuse, and Broken 
Brick. 

If the question be asked concerning 
any of these, wiiether their embodiment 
in concrete is safe, the answer must be 
in the negative, but qualified with the 
statement that many have taken the 
risk of using them and are none the worse. 
It may be interesting to set out the nature 
of the risk with each of the materials 
mentioned. 

With Blast Furnace Slag the danger 
lies in the presence of sulphur which may 
exist as sulphide of calcium or iron and 
sulphate of lime. When present as 
sulphide there is liability to oxidation 
with consequent expansion, and there is 
the possibility that the concrete will have 
the unpleasant odour associated with 
sulphuretted hydrogen, and also a green- 
ish hue. Further, when used in con- 
nection with reinforced concrete there is 
a tendency to promote the rusting and 
expansion of the steel work. 

When sulphate of lime is present in 
slag, the tendency of the sulphide to 
oxidise is implied and there is also the 
possibility of the sulphate of lime retard- 
ing the setting of the cement. Chemical 
analysis is sometimes resorted to in an 
attempt to decide the character of slag, 
but although a slag containing 2 per cent, 
or more of sulphate of lime might be 
condemned, it is impossible to base on 
chemical analysis a statement that any 
particular slag is perfectly safe for use. 

With Coke Breeze, the danger also 
lies in the presence of sulphur, but as 
Breeze concrete is seldom used for any 
work of an important nature, expansion 
short of disintegration may go unnoticed. 
Destructor Refuse may on occasion 



E 



:ON5TRUCT,IONAii 



NEW BOOKS. 



be a curious conglomeration, and it is 
hardly possible to classify the risks which 
are possible with Destructor Refuse. 
Any uncalcined material of an organic 
nature may, of course, be dangerous. 

With Broken Brick the presence of 
adherent lime mortar or plaster can be 
detected with the eye and such impurities 
constitute obvious risk. In the absence 
of this, however, there is still the possi- 



bility that the brick may contain sulphur 
compounds usually derived from the 
presence of pyrites in the clay from which 
the bricks were produced. Certain 
bricks from the Eastern Counties are 
notoriously unsafe for use in concrete 
on account of their sulphur content, but 
in the case of bricks, a chemical analysis 
will generally suffice to show whether 
the material is safe to use. 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books which have appeared during 
the last few months. 



Reminiscences of a Municipal Engineer. 
By H. Percy Boulnois, M.Inst.C.E. 

St. Bride's Press, Ltd. 

The reader who has not had the privi- 
lege — and it is a privilege — of the personal 
acquaintance of Mr. H. Percy Boulnois, 
may be forgiven if, on seeing the title 
of this work, he passes it by as being of 
little interest to him. Should he do so, 
the loss will undoubtedly be his, since 
the book is of an uncommon type, full 
of human interest, and the reader, being 
taken behind the scenes, is afforded 
intimate glimpses of the man himself. 

In a general sense the duties of a 
municipal engineer are known to most, 
but very few, we fancy, realise the very 
wide scope of his work as revealed in the 
operations described in these pages. To 
the lay mind the work of the municipal 
engineer is something quite technical 
and matter-of-fact, but the reader will 
be surprised to learn how much romance 
and humour are associated with it. Mr. 
Boulnois' light touch brings this out 
very clearly, and the style of his descrip- 
tion adds interest to many of the works 
the engineer, in the course of his " daily 
round and common task," is called upon 
to carry out. 

This book should also be of practical 
a.ssistance to young engineers since the 
<letails of many pieces of work of excep- 
tional character therein described show 
great resource in overcoming difficulties. 

In addition to his experience in La 
V^endee, Jamaica, and at the Metro- 
politan Hoard of Works, Mr. Boulnois 
has held tlie olliccs of Municipal I-inginccr 



and Surveyor of Exeter, Portsmouth 
and Liverpool, and after spending some- 
thing like fourteen vears as one of His 
Majesty's Inspectors of the Local Govern- 
ment Board has now retired into private 
practice after a long, distinguished and 
honourable career of some forty-one 
years of strenuous life devoted to munici- 
pal engineering. 

The book is full of interest from cover 
to cover, from the charming dedication : 

" To her, to whom I owe all mv happi- 
ness and any success I may have 
achieved in this life, to my dear 
wife." 
to the final sentence : " Speculations as 
to the future are as fascinating as 
memories of the past. We laugh some- 
times at the so-called barbarism and 
ignorance of the people who lived a 
hundred years ago, forgetting that a 
hundred years hence we shall, in turn, 
be laughed at for our present feeble 
efforts. 

" We are children still, wayward and 
wistful, 

With one hand we grasp the familiar 
things 

We call our own, whilst with the other. 

Resolute of will, we grope in the dark 

For that the day will bring." 

Le^vis Cr Chandler's " Popular Handbooh 
for Cement and Concrete Users." 

Wc arc asked t'> state tliat tl.e price of 
this book, reviewed in our January number, 
is now i8.'<. The Publishers are Messrs. 
Henry Fn)W(le, Hodder & Stoughton, 17, 
Warwick Square, K.C.j. 



133 



NEW METHODS OF CONSTRUCTION. 



[coNCREra 



■ > '■ " — "' -vn " 





^ 



'^: 



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V 




NEW METHODS 

OF 
CONSTRUCTION 



IE a.t.«x.J,y>:'>.-"T.N.-tt-^^«t 




A SIMPLE CONTRIVANCE FOR HOLDING DOWN RAILS TO CONCRETE 

FOUNDATIONS. 

Whilst on a recent visit to probably the largest public works undertaking being 
carried out in this country our interest was roused in a detail of construction which 
may be novel to many interested in railway or tramway construction. 

The detail in question was the simple and effective method employed on an 
extensive scale in the attachment of fiat-bottomed rails to reinforced concrete slab 
foundations. We were informed that the svstem was adopted only after much 
thought and repeated experiments with existing types of attachments. It was 
found that these latter whilst leaving much to be desired from a practical and econo- 
mical point of view even when used with plain concrete foundations were far more 
unsuitable when the problem was further complicated by the necessity due to bad 
foundations of reinforcing the concrete with double-layer interlocked reinforcement. 

As we consider that the solution may be of interest to our readers, we herewith 
give a brief description illustrated bj^ a photograph of work in progress and Figs. 
1 to 5, in which latter — 

Fig. 3 is a section on line^ii of Fig. 4 and shows the tramwav rail/ in elevation. 

Fig. 4 is a cross section through the rail / on line 22 of Fig. 3. 

Fig. 5 is a cross section through the slot in the concrete raft e on line 33 of Fig. 4. 

The procedure is as follows : — 

After the formation has been levelled off and the interlocked double-layer rein- 
forcement laid in position the ganger attaches to the top layer of steelwork the mark- 
ing out lines giving approximately the positions of the rails at desired spacings. On 
these lines he fixes vertically on the formation and transversely to the rails the tapered 
templates a (in Fig. i) each fitted at the rebated lower end c with a loose thin slotted 
base plate h of thin stamped out metal shown in plan in Fig. 2. 

Through a hole in the top of each template is passed a rod or bar connecting 
three or more templates together. The top of the horizontal bar is levelled off to 
rail level by packing up under the base plate h with sand. After all the templates 
are thus set up the concrete is put in position up to the lower edge of the iron band 
h on the template, the top edge of the band being identical in level with the underside 
of the rail /in Figs. 3 and 4. After the concrete is partly set the templates are slightly 
eased and subsequently removed completely when the concrete has set hard. This 
results in slotted holes in the concrete surrounded at the bottom of the raft by the 
flat slotted base plates h. 

The rails are now brought on the site and laid in position on the concrete at the 
required level, being packed up on small premoulded concrete wedges or other suitable 
packing. Into the tapered holes in the concrete are dropped " L" headed bolts d having 
close up against the head a short length of square neck -p. The bolt head is pushed 
down into the cavity, left below the base plate by the removal of the projecting lower 
end of the template, until the square neck is below the base plate. The bolt is then 
turned 90°, and pulled up until the square neck fits again in the slot of the base plate 
and so prevents the bolt from being turned round when the nut is being tightened. 
For convenience in fixing, the bolt is supplied by the makers with a notch cut in the 
top of the screwed end, which notch indicates the position of the "L" shaped head 
of the bolt. 

134 



», CONSTKUCnONAll 
A ENGIT^XERING -^ 



NEW METHODS OF CONSTRUCTION, 




f 



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NEW METHODS OF CONSTRUCTION. [CONCRETE 



The bolt can be used to secure the rail either by passing through a hole (iriile<l 
in the base of the rail or as shown ii« Figs. 3 and 4 by means of a bent clip g. 

After the bolt nuts have been screwed down and the slotted holes filled with sand 
to within half an inch of the concrete surface the concreting is resumed and great 
care is taken thoroughly to pack and grout the concrete under the rail and so prevent 
any subsequent disastrous " pumping " action so common with rails badlv bedded 
and fastened down. 

It will be evident that the comparative cost of this procedure is negligible and 
consists in a small capital outlay in liard wood templates together with a few pence 
per hole for the cost of the thin stamped out bed plates h. 

The necessity for anchorage consisting of inverted short lengths of rail buried 
in the concrete and for the packing up of the rails in their exact position over the 
trench before concreting is eliminated, and skilled supervision also in setting out, is 
reduced to a minimum. This latter is obvious as no careful setting out is required 
in fixing the templates as the resultant 5 in. or 6 in. length of the slot in the concrete 
gives ample margin for any slight error on the part of the ganger. Also the adjust- 
ment to rail level of the rod passing through the holes in the top of each template 
automatically ensures : — 

(a) correctness in the level of the surface of concrete e. 

{b) ample uniformly regulated space for packing and grouting under the rail. 

■(c) uniform length of bolts. 

In the case of renew^als due to settlement, wear, or otherwise, it is a simple matter 
to takeout and renew the bolts and to securely attach the rail again without having to 
place imperfect reliance on green immature concrete or grout in lewis holes or such-like. 

The above system, which has been found applicable to other uses in securing 
structural members other than rails to either plain mass concrete or to concrete rafts 
is the invention of Mr. J. H. Walker, A.M.I.C.E., who contributed the interesting 
article on overhead strut cablewav cranes illustrated in our issue of February 1920, 
under the heading of " Notes on a suggested Solution of the Housing Problem." 
We understand that Messrs. The Walker-\\'eston Co., of 7, Wormwood Street, 
E.C.2, have undertaken the commercial development of the system in all its applica- 
tions in conjunction and otherwise with their now well-known system of pyramidal 
interlocked double-layer reinforcement. 

QUESTIONS AND ANSWERS 
RELATING TO CONCRETE. 

In response to a very general request we are re-starting our Questions and 
Answers page. Readers are cordially invited to send in any questions. These 
questions will be replied to by an expert, and, as far as possible, they will be 
answered at once direct and subsequently published in this column for the infor- 
mation of our readers, where they are of sufficient general interest. Readers 
should supply full name and address, but only initials will be published. Stamped 
envelopes should be sent for rei)lies. — Ed. 

Question. — E. C. L. writes: — Is rein- reinforcement is a necessity. In America 

for'cement necessary or advantageous iu a many of the lightly trafficked roads are 

concrete road ? of plain concrete. 

Answer. — This really resolves itself 2. Is reinforcement advantageous? 
into two questions which are closely Undoubtedly, yes. In the first place, 
related, and it is difficult to answer one the concrete in a road which is not rein- 
without referring to the other. forced must be thicker than that in a 

I. Is reinforcement necessary? This road where reinforcement is employed, 

is entirely a question of circumstances. if the same degree of strength is to be 

In cases where the road bed is bad, rein- attained. And further, where there is 

forcement is absolutely necessary. If any tendency to crack, the reinforcement 

the bed is doubtful it is certainly ad- spreads this tendency over a wide area 

visable that the road should be rein- with the result that the cracks, where 

forced. they exist at all, are so minute as often 

Then again, where heavy traffic has to to be invisible and therefore the road 

be provided for, we should say that slab suffers no detriment. 

136 



i 



CON5TCUCT1CM, 
ENGIME£RING 



(An 



MEMORANDA . 




MEMORANDA. 



tfss^^^a 



AjtjJ 



Meiiioraiidii and Xeas Hems are presented under this heading, with occasional 
editorial comment. Authentic news will be welcome. — Ed. 



Cost of Laying Block and Brick, and Comparative Strength. — Writing to our 
contemporary, Concrete, U.S.A., ^Ir. H. G. Krum gives some interesting particulars 
of his experience regarding block and brick laying. He says : — 

" In bidding on a three-storev factory building to be erected in the near future 
in St. Paul, we had occasion to prepare a table to show the owner and architect the 
cost of erecting block walls. The first two storeys of the building had to have i6 in. 
walls, in order to meet with the city requirements. We did not happen to have 
very many i6 in. tamp units on hand, so had to figure two 8 in. blocks for each course, 
using a course of i6 in. blocks every fifth course for a header. 

" This table may be of interest in retelling the story that the cost of erecting 
blocks is very much less than laying up brick. It also shows that a well-made concrete 
unit will carry a much greater load than common brick. The cast units on hand 
showed a test of 2,000 lb. to the square inch ; the tamp units a test of 1,200 lb., 
and the brick (sand lime) 450 lb." 

CoMP.\R.\TivE Cost per 100 So. Ft. of 16 In. \V.\ll M.\teri.^l, L.\bour .\.nd Mort.\r Cost at Presext 

Market Prices. 



Cast I — 12° 

and 1-4" 
alternately. 



Tamp 2 — 8' 

^vith 16' 
block for Hdr. 



Brick — Solid 
sand lintie. 



Material cost on job (no hoisting, etc.) . 

Labour laying 

Mortar cost 

Approximate cost per 100 stj. ft. of 16 in wall 

Material required per 100 sq. ft. of wall . 

Ultimate crushing strength per lin. ft. of wall . 
Safe load (10 per cent.) ....... 

Blocks laid per day 

Blocks per cu. ft. of mortar 

Mortar per cu. ft 

Mason per day 

Helper per day 



S55-I3 
15-28 

3-75 


S54-00 

15-72 

4-92 


853-34 
35-55 

10-20 


S74-I6 
73-12" 


874-64 
182-8' 


899-09 
2667 



73- 4 

208,000 

20,800 

123 

24 



15-16' 

HI ,600 

11,160 

200 

32 



86,400 

8,640 

1,200 

156 

So -Go 

Sio'oo 
$6-oo 



Effect of Paint on Reinforcement. — A series of tests, undertaken by the I'nited 
States Bureau of Standards to determine the effect of preservative coatings on the 
bond resistance of reinforcing bars embedded in concrete, has resulted in the following 
conclusions being arrived at : — The maximum bond stress developed by paintetl bars 
was gcncrallv considerably less than the bond resistance of unpainted bars, but the 
reduction in nia.xinium bond resistance (\uc to galvanising and similar processes 
was less than tliat due to painting. 

Concrete Cross Roads Signs. 'I'lie Illinois Division of Highways has announced 
that concrete niilea^^c jiosts, surmounted b\- Illinois-sliaped concrete markers, which 
together will stand (> ft. Iiigli, are to be placed at all cross roads on three state liighwaNTS. 

137 



MEMORANDA. [CONCBETE) 

Placing Concrete in Cold Weather. — In our December number we published an 
article on this subject, and in further reference to the information given there, the 
accompanying chart and instructions, which more or less embody the points empha- 
sised in our December number, may be useful. We are indebted to the Portland 
Cement Association of Chicago for this diagram and the accompanying text. 




Aggregates and mixing water 
should be heated to about 1 50 
degrees Fahrenheit in order to 
insure that concrete is of the 
proper temperature when 



_placed. 



Concrete when placed in 
forms should have a temper- 
ature not less than 70 degrees 
Fahrenheit. 

Heat aggregates and mixing 
water when prevailing tem- 
peratures range between 40 
and 50 degrees Fahrenheit. 

When temperature is likely 
to fall to freezing or below, 
heat materials and protect 
concrete from freezing. Warm 
forms. Remove all snow and 
ice. Leave forms in place un- 
til concrete is strong enough 
to be self-supporting. 



Heat aggregates and mi.xing water so that concrete when placed will have a temperature not lower than 70 degrees. 

Place concrete in the forms immediately after mixing so that none of the heat will be lost. 

Protect concrete as soon as placed in order to retain the heat. Canvas covering, sheathing or a layer of clean straw 
will furnish sufficient protection for some work. Where work can be enclosed, open coke stoves or salamanders may be 
used. In severe weather such protection should be continued for at least five days. 

Be sure concrete is strong enough to bear load before forms are removed. Examine by pouring hot water on concrete 
or by heating in some other way to be sure concrete has hardened, not merely frozen. 



CONCRETE AND HOUSING SCHEME. 

Ashburton. — The Ashburton Urban District Council has instructed its Architect 
to invite alternative tenders for the erection of houses in brick and concrete. 

Ayr. — The Ayr District Committee of the Ayrshire County Council has instructed 
its Road Surveyor to obtain tenders for the erection of fourteen houses at the Old 
Mill, New Cumnock, in brick and in concrete. 

Batley. — The General Works Committee of the Batley Town Council has passed 
plans for ten concrete houses, to be erected in Grange Road, Staincliffe, for Councillor 
G. R. C. Fox of Stainchfie Hall. 

Bath. — An inspector of the Ministry of Health has informed the Bath Town Council 
that H.M. Office of Works is prepared to erect fifty concrete houses in the city, and the 
Council's Architect has been instructed to obtain further information on the subject. 

138 



E 



^^^il^l.^^ MEMORANDA. 



Hucknall. — A deputation from the Hucknall Urban District Council has visited 
the Birmingham concrete housing scheme, and has reported in favour of the adoption 
of concrete construction for the Hucknall housing scheme. 

Kirkintilloch. — Owing to the difticulty of obtaining bricks, the Kirkintilloch Burgh 
Council has empowered the Housing Committee to acquire plant for the manufacture 
of concrete blocks, if necessary. 

Leeds. — The interest in concrete houses taken by local authorities may be gauged 
by the fact that no fewer than 500 of them have sent representatives to Leeds to inspect 
the concrete housing scheme at ISIeanwood. These houses are being erected by Messrs. 
William Airey & Son, Ltd., on the slab system. 

Manchester. — Two bungalows are to be built, as an experiment, on the Mount 
Road Estate, Manchester, by the Manchester City Council, on a svstem of concrete 
block construction evolved by Alderman James Johnston. In this system pre-cast 
concrete units, twenty-eight in number, are used, and placed in position by crane 
power ; the roofs are formed of concrete slabs. It is claimed that the bungalows, 
which contain a large living-room, three bedrooms, kitchen, scullerv, and usual offices, 
can be built in quantities of from 50 to 100 at ;£50o or ;(6oo each, as compared with 
houses with similar accommodation being built by the ^lanchester Corporation at 
from /i,ooo each. 

Merthyr. — The Merthyr Housing Committee has sent to the Housing Commis- 
sioner a tender of Messrs. Dorman, Long & Co., for the erection of steel and concrete 
" Dorlonco " houses at the following prices : non-parlour houses, £^9^ each ; parlour 
type houses, ;;^i,oi7. 

Newcastle-on-Tyne. — ^'Ihe Newcastle-on-Tyne Corporation has signed contracts 
for the erection of 265 houses at Walker, 50 of which are to be of concrete. 

Onnskirk. — As the result of experiments with concrete blocks, the Ormskirk 
Urban District Council has decided to apply to the Ministry of Health for a loan of 
;^22,ooo for the purchase of plant and materials for the manufacture of concrete blocks 
for use on its housing scheme. 

Plsrmouth. — The Housing Committee of the Plymouth Town Council has recom- 
mended the erection of 250 houses on the " Duo Slab " concrete system, and also the 
erection of a sample pair of concrete-slab houses. 

Rawmarsh. — The Rawmarsh Town Council proposes to enter into a contract with 
Messrs. Hopkinson & Co. for the erection of a further seventy houses on the High 
Road site (making 100 in all) on the " Dorman Long " system. 

Rugeley. — The Rugeley Urban District Council has decided to erect concrete 
houses by direct labour, and plans have been prepared by the Surveyor and submitted 
to the Housing Commissioner for the area. 

Salisbury. — An interesting experiment is being tried by the Salisbury Town 
Council, in conjunction with the local Master Builders' Association, in the direction of 
employing imskilled ex-Service men on its housing scheme. Twcntv houses have 
already been commenced, and some fifty unemployed ex-Ser\nce men engaged. The 
houses are being built of concrete blocks, manufactured on the site, and careful costs 
are to be kept. The scheme has the approval of the Ministry of Health. 

Whiston. — The Whiston Rural District Council has passed plans for four concrete 
houses at \\ arrington Road, Bold, two concrete houses at Mill Lane, Rainhill, and eight 
concrete houses at Holt Lane, Whiston, for the Lancashire County Council. 

The Ministry of Health. — We desire to call attention to the General Housing 
Memoramliim (No. .|o) recently issued which deals with the problem of Smoke .\bate- 
ment in connection witli the design and equipment of dwellings. Copies of this 
memorandum can be obtained from the Ministry of Health on apjilication. 

PROSPECTIVE NEW CONCRETE WORK. 
Blairgowrie. I lie IMairgowric District Comniitlcc of tlic IVrtli County Council 
is considering tlic question of repairing four large breaks in the embankments of the 
River Kriclit, at a cost of ;{;3,5oo. 

139 




t: 







^ 2 X 

5 ^ S 

, w ^ g 

^ N 0^ r 



<: 



140 



Please mention this Journal when writing. 



&^y,SI!^J.^^ MEMORANDA. 



Bradford. — The Streets, Drainage and Works Committee of the Bradford Corpora- 
tion has recommended the Corporation to purchase a concrete mixer, and stone- 
breaker, and other machinery for use in road works. 

Bridge of Allan. — The Bridge of Allan Town Council has decided to apply for 
powers to construct a new waterworks, at a cost of ^25,270. 

Brierley Hill. — The Brierle^^ Hill Urban District Council has agreed to the con- 
struction of a new canal bridge, at a cost of /2,5oo. 

Carnarvonshire. — The Carnarvonshire County Council has agreed to the con- 
struction of a reinforced concrete bridge at Croesar, at a cost of /5,700. 

Colchester. — The Harbour and Navigation Committee has recommended the 
Colchester Town Council to submit a scheme of harbour improvement to the ^Ministry 
of Transport. 

Crewe. — The Crewe Town Council has instructed the Borough Engineer to prepare 
designs for alternative tj'pes of bridges at Alton Street. 

Dartmouth. — The Dartmouth Town Council is considering a report by Messrs. 
J. & W. Purves, Consulting Engineers, of Exeter, for the construction of a new reser- 
voir, at a cost of ^34,000. 

Grimsby. — The Town Council has authorised the construction of six pairs of 
elevated concrete silos, at a cost of /3,2oo, in connection with a scheme for unloading 
railway trucks in the yard of the Highways Department. 

Lambeth. — The Lambeth Borough Council has decided to offer no objection to the 
construction of a steel and concrete extension of the stand at Kennington Oval by 
the Surrey Cricket Club. 

Millom.— The Millom Urban District Council has decided to construct a new reser- 
voir, with a capacity of 20,000,000 gallons, at a cost of ;^50,ooo. 

Ruishp-Northwood. — The Ruislip-Xorthwood Urban District Council has decided 
to apply to the Ministry of Health for sanction to borrow £430 for the construction of 
a concrete retaining wall at the Eastcote Pinner Road. 

Sidmouth. — The Sidmouth Urban District Council has adopted a report of its 
engineer, wliich provides for a scheme of sea defence works at a cost of £27,000. 

Stirlingshire. — The Stirlingshire County Council is promoting a Provisional 
Order for authority to construct new reservoirs and embankments, at a cost of £^240,045. 

Yarmouth. — The Yarmouth Port Committee has reported that an immediate 
expenditure of £214,120 is essential for the proper repair and upkeep of the harbour. 

Yeovil. — The Yeovil Town Council has applied to the Ministry of Health for 
sanction to borrow £800 for the erection of a concrete shed, and to instal therein a 
travelling pulley block. 

NEW METHODS AND MATERIALS. 

The following is a further list of materials and new methods of construction 
approved by the Standardisation and Construction Committee : — 

A. J. Dunn, 5a, Temple Koiv, Birmiiti:ham. — The "Con-cog" system of concrete construction 
consists primarily of pre-cast iiiterlorking units, including stancheons, beams, joists, purlins, roof, 
floor and walling slabs, chimnev-flues, door, window and other dressings. 

Repinald Brown, Osterley, Lone.ford Avenue, Southall. — The " Elzed " System. — ^The system is one 
of pre-cast units designed to make even the setting out of a building a comparatively simple operation, 
whilst the construction is such as to give a perfect bond in walls. 

Features of the system are the use of sill-plates and Z-shaped wall-blocks forming a series of hollow 
rectangles whi( h can be left hollow or filled witli poured concrete. 

/. E. Wilkes, A.M.I.C.E., City Engineer, Oxford.— The method of building is a cavity wall with 
plain concrete slabs, headers being provided alternately with stretchers in each course. 

W. C. Murchison, c/o Tasmanian .ipent (ieneral, Australia House, Strand, W.C. — A system of 
shuttering which consists of the use of angle steel uprights, which are firmly held together by angle 
irons at top, fastened in such a way as to be readily adjustable to any class of liuilding, with steel sheets 
of various lengths wliich are moved upward two feet per day, thus forming a monolothic wall. 

/. Weston, 2, Harewood Place, Hanover Square, W.y. — the " Weston " System. — The blocks are 
made of terra-cotta or clinker. In the former case the space between the wings is tilled with clinker 
concrete. The blocks are placed in position with wings adjoining and one above the other, no bedding 
in mortar being necessary. 

Centreing is erected on the outside face, and concrete is poured between this and the blocks. A 
small vertical md is placed in each rib and also every 18 inches horizontally. The finished wall is 3 
ribbed structure of reinforced concrete. 

141 




CONCKEJTE/^^'''^^™"^'^^'"^ 



EISTGINE^ERnSTG 






IS efficient, portable and handy to operate. 

Having only two road wheels it can readily be 
mancEuvred round awkward corners or into confined 
spaces, and can be discharged, if desired, directly into 
forms. 

It entirely supersedes the inefficient and laborious 
process of mixing by hand and shovel, 
ensuring that every grain of sand and 
stone is coated with a thoroughly hydrated 
cement mortar. 



The saving of time and labour effected by 
the Victoria H.M. Mixer soon pays for the 
machine. 

May we send you particulars ? 



STOUffiM^ITI 

(MIXER DEPARTMENT) 

1 I.VICTORIA ST.. LONDON S.Wl 



m 



142 



Please mention this Journal when writiag. 



I&^?.S;g^{.^^ MEMORANDA. 

TENDERS ACCEPTED. 
Housing. 

Cheltenham. — ^The Cheltenham Town Council has accepted the tender of Messrs. W. T. Nicholls, 
Ltd., for the erection of 20 steel and concrete houses on the " Dorman Long " system, at a cost of 
£998 each (subject to modification). 

Houghton-le-Spring. — ^The Houghton-le-Spring Rural District Council has accepted the tender 
of Messrs. W. Airey & Sons, Ltd., of Leeds, for the erection of 213 Type " A " concrete houses at 
£870 per house, and 137 Type " B " concrete houses at £990 per house. 

Leyland. — ^The Leyland Urban District Council has accepted the tender of the Leyland and 
District Building Employers' Association for five concrete block houses, at £905 19s. each. 

Llanelly. — ^The Llanelly Town Council has accepted the tender of Messrs. W. T. Nicholls, Ltd., 
for the erection of 150 steel and concrete houses, on the " Dorman Long " system, at a cost of £148,057. 

Newcastle-on-Tyne. — ^The Housing Committee of the Newcastle-upon-Tyne Corporation 
has accepted the following tenders for the erection of concrete houses, in groups of twenty, on the 
Walker Estate : — ^S. Miller, North Street, 79 houses at £72,859 ; G. G. Carr, Worswick Street, 81 houses 
at £73.991 ; A. Anderson, Biddlestone Road, 18 houses at £16,558 ; Braithwaite & Co., Black White- 
field Terrace, 19 houses at £17,449 ; J- S. Hetherington, Westgate Road, 18 houses at £16,558. (AU 
of Newcastle-upon-Tyne.) 

General. 

Bromley (Kent).— The Works and Stores Committee of the Metropolitan Water Board has 
recommended the acceptance of the tender of Messrs. R. Robinson & Co. for the construction of a 
covered service reservoir at Bromley, Kent, for the sum of £53.357 13s. 7d. 

EsQUiMAULT (Canada). — ^The contract for the construction of a dry dock at the Esquimault 
Navy Yard has been awarded to Messrs. T. P. Lyall & Sons Construction Co., of Montreal, at £860,000. 

Mansfield. — The Town Councjl has accepted the tender of Messrs. Lane Bros., of Mansfield, for 
the construction of about 1,800 yards of concrete tube sewer, etc., for the sum of £28,439 i^s. 6d. 

Southend-on-Sea. — The Town Council has accepted the tender of Messrs. Millar's Trading Co. 
for the supply of concrete mixing plant, for the sum of £300. 

TENDERS INVITED. 

Willesdem. — February 14. For the erection of seventy-six concrete houses on the " Fidler " 
system, for the Willesden Urban District Council. Plans, etc.^ from the Borough Engineer, Municipal 
Offices, Dyne Road, Kilbum, N.W. 

Ely. — February 17. Forerection of 8 houses at Wilburton, for Ely Rural District Council. Plans, 
etc., from Messrs. Spalding, Myers & Theakston, Architects, 12, New Court, Lincoln's Inn, W.C.2. 

East Grinstead. February 21. F"or erection of forty houses, by alternative methods of con- 
struction, for the East Grinstead Rural District Council. Plans, etc., from Mr. Charles Turton, 
Architect, 36, High Street, East Grinstead. 

HoLLiNGwoRTH. — F'ebruary 22. For erection of twelve houses for the Urban District Council. 
Plans, etc., from Mr. H. Wilson, Clerk to the Council, Norfolk Square, Glossop. Deposit £3 3s. 

Maldon. — F'ebruary 22. I*"or erection of eighty-eight houses for the Maldon Urban District Coun- 
cil. Plans, etc., from Mr. W. Almond, Surveyor, 6, Market Hill, Maldon. 

South .'\frica. — Tenders are invited by the Government of South Africa for the construction of 
one grain elevator (30,000 tons capacity), at Cape Town ; one elevator (42,000 tons capacity), at 
Durban ; and thirty-ft)ur smaller grain elevators in various districts, in connection with the South 
African Railways and Harbours, lull particulars from the High Commissioner for the Union of South 
Africa, 32, Victoria Street, London, S.W.i. Sending-in day. May 2. 



" CONCRETE ROADS, 

a Technical Handbook, carefully Edited and Profusely Illustrated, intended 
primarily for Borough Surveyors, Municipal Officials, Engineers, Road 
Contractors and all others interested in Modem Road Construction. 



9» 



Now Ready, Ss. net. By Post, 8s. 6d. 



From CONCRETE PUBLICATIONS. LTD. (Publishing Dept.). 

4. Catherine Street, ALDWYCH. W.C.2. 



M.^ 



MEMORANDA. 



iCDNCBETEI 



CONCRETE MACHINERY. 

A New Concrete Mixer. 

— A new concrete mixer has 
recently been put on the 
market by Messrs. R. H. Kirk 
& Co., of Colhngwood House, 
St. Peters, Newcastle-on- 
Tyne. The mixer, of whicli 
we give an iUustration, is a 
double-motion mixer and can 
be operated either by hand or 
power, and it is said to adapt 
itself equally well to wet, 
semi-wet or dry ingredients. 
Among the advantages claim- 
ed are the following :• — It is a 
batch mixer, which ensures 
that the mixture is composed 
of the exact required propor- 
tions ; certainty of action ; the 
ploughs revolving in opposite 
directions give a balanced 
effect, thus reducing working 
depreciation to a minimum ; 
there is a wide range of ad- 
justment and simplicity in 
design. Further, the ingre- 
dients are turned over four times with every revolution ul lliu ploughs, and very little 
power is required. The discharge of the mixed materials is effected through a sliding 
door in the bottom of the mixing pan. 

TRADE NOTES. 

Hayes System of Concrete Cavity Walling. — In our December number we gave an 
illustrated description of this system on page 839. Messrs. Hayes ask us to add that 
the shuttering in connection with their system is very simple to fix, and, spread over a» 
number of houses, the cost is very small. It has a long life, and the number of times 
it can be used is unlimited. The cost of putting the concrete into position is also 
considerably reduced, and walls can be erected at a reduced cost as against brick 
or other walls erected by skilled labour. 

For further particulars readers should apply to Messrs. W. P. & P. G. Hayes, 
Lyme Street, Warrington. 




SERVICES OFFERED. 

rONTRACTOR'S AGENT with consider- 
able experience in Reinforced Concrete Con- 
struction and Public Works generally, seeks re-engage- 
ment. Age, 40. Gocd executive ability. First class 
references. Box 189, c/o Concrete and Constructional 
Engineering, 4, Catherine Stieet, London, W.C.2. 

nrO ARCHITECTS, ENGINEERS AND 
-•■ CONTR.^CTORS. Reinforced concrete and 

steel structures of all descriptions designed with full 
working drawings and details by experienced engineers, 
moderate terms. Write Box No. 187, c/o Concrete and 
Constructional Engineering. Also Box 188. 

AGENCIES WANTEd7 

COLE AGENCIES WANTED by well- 
'^ known, reputable and established English 

engineering firm, represented all over the world, for 
Contractors' or Municipalities' small Engineering 
Equipment, which must be first-class, competitive in 
price, and in constant large demand. British made and 
patented preferred ; if Colonial or Foreign, privilege of 
manufacturing in Ingland required. Big sales assured 
for the right equipment. Write gi\-ing details to Box 
188, c/o Concrete and Constructional Engineering, 4, 
Catherine Street, London, W.C.2. 

144 



APPOINTMENTS VACANT. 

"DEQUIRED for India Factory Man- 
ager for Concrete Product Works. Must have 
good organizing and technical (mechanical) qualifica- 
tions ; also preferably knowledge reinforced concrete 
works and experience of Indian labour. Write stating 
age, experience, etc., to Box " S.E.," Davies & Co., 95, 
Bishopsgate, E.C.2. 

ASSISTANT Engineer Speciahst in 
reinforced concrete design and practice required 
at once for Bombay. Good salary. Apply H. Wolfi, 
18, Park Road, Hampton Hill, London, S.W. 



MISCELLANEOUS. 

T-HE PUBLIC WORKS DEPART- 

-•■ MENT, KENYA COLONY, are desirous of 

receiving trade CATALOGUES dealing with the BUILD- 
ING and ENGINEERING trades. Any statements of 
approximate prices with trade and other discounts will 
be of great \'alue and will be treated as confidential. 
Catalogues should be posted to the Honourable Director 
of Public Works, P.O. Box 62, Nairobi, KenyaColony. 



CONCRETE 

AND 

CONSTRUCTIONAL ENGINEEmNG 



Volume XVI. No. j. London, March, 1921. 

EDITORIAL NOTES. 



THE BUILDING TRADES' EXHIBITION. 

THE'second post-war International Building Trades' Exhibition is to be held from 
April 12 to 26, and the venue, as last year, is to be Olympia. Space has been 
readily taken up, and the show promises to be as successful as last year's. From 
the point of view of concrete, last year's exhibition was, no doubt, the most 
interesting ever seen in this country, as it was held after a lapse of six years and 
embodied not only the progress made during the period of the war but also demon- 
strated the extent to which the material was being used to overcome the housing 
shortage. During the past year large numbers of concrete houses have been built 
or commenced on the systems on view at last year's Exhibition, audit is certain 
that many new ideas will be open to inspection at the forthcoming show. Although, 
however, housing may be expected to dominate the constructional side of the 
Exhibition, it is to be hoped other adaptations of concrete will be on view, such as 
farm buildings (poultry houses, cattle stalls, pigsties, etc.), fencing, sign-posts, 
telegraph posts, railway sleepers, tanks, drinking troughs, and many other pur- 
poses for which concrete is being used with advantage and economy. 

We hope, also, that the artistic side of concrete will not be overlooked, and 
that those interested and the general public will be afforded an opportunity of 
seeing sample slabs with exposed aggregate, showing the delightful effects that 
can be obtained by this treatment. Such a demonstration would go a long way 
to dispel the view, which is still often heard, that concrete can only be a dull, 
uninteresting, monotonous-coloured material. 

A list of some of the firms who have taken up space on the ground floor for 
the forthcoming Exhibition will be found in another part of this issue. 

CONCRETE AND ARCHITECTURE. 

At a meeting of the Royal Institute of British Architects last month Mr. W. E. 
Willink, F.K.I.B.A. (of Messrs. Willink cV Thicknesse, the architects for the build- 
ing), gave an account of the Cunard Building, Liverpool, which was illustrated 
and described in our issue for November, 1917. This building, which is one of 
the finest erected in this country in recent years, is of reinforced concrete with 
stone facing, and speaking of the concrete work Mr. Willink said : " I need hardly 
enlarge on tlie merits of reinforced concrete. One of its cliief drawbacks is one 
which affects not us, but maybe our grandchildren. When it is decided to destroy 
the Cunard Building to make way for a thirty-storey building on its site, I feci 
sorry for the contractor who has to do it. I suppose, however, one could hardly 
expect a Iniilding proprietor to regard as an important quiUity in his building 

145 



SLAB CONCRETE ROADS. [CQNCBETfl 

that facility of demolition which might appeal to his great-grandson." When 
considering the merits of a building there is so often a tendency to do so on its 
external appearance only that it is a pleasure to hear such an eminent architect 
as Mr. Willink speak in euoglistic terms of the reinforced concrete work which, 
after all, in many cases makes the design possible. 

SLAB CONCRETE ROADS. 

Although concrete roads are now past the experimental stage, and are proving 
their superiority over other forms of road construction by the test of use under 
practical conditions, the concrete roads laid in this country up to the present 
have, so far as we are aware, all been built in situ, with some form of reinforce- 
ment. An experimental section of roads laid with pre-cast concrete slabs which 
has been built at Taunton will, therefore, be watched with considerable interest. 
The costly operation of opening up and relaying roads when it is necessary to 
repair existing underground gas, water or electricity mains, or sewers, or to lay 
new ones, is common to all types of roads, and it is partly with the object of 
minimizing this item of expenditure that the experiment is being made. When 
such excavations are required under a road constructed with slabs, the necessity 
for breaking up the surface and re-paving with new concrete is eliminated ; it is 
only necessary to lift the slabs and replace them when the repairs have been 
carried out. A further advantage is that when the slabs become worn they can 
be replaced with new slabs from stock in a very short time, and traffic can be 
resumed without the usual delay of waiting for the new concrete to set. In the 
construction of new roads, also, as the surface is laid with matured pre-cast slabs, 
the usual period of three weeks or so which has to be allowed whilst roads laid 
in situ are setting is dispensed with, and thus one of the objections often levelled 
at concrete roads by local authorities is removed. 

The experiment in question is being carried out at Taunton, and was de- 
scribed by Mr. J. F. Shellard, A.M.Inst.C.E., the Borough Engineer, at a meeting 
of the Institution of Municipal and County Engineers last month. The section 
on which the experiment is being carried out is some 20 ft. in length in a busy 
street. The slabs are 3 ft. 6 in. long by 2 ft. wide by 5 in. thick, laid to break 
joint. For the purposes of the experiment the slabs are made of various aggre- 
gates, some being reinforced and some not. No special foundations have been 
prepared, but the slabs are embedded on mortar composed of sand and cement in 
the proportion of six to one. Expansion joints are provided by leaving a space 
of I in. between the slabs and filling it in with a tar compound. In a table of 
comparative costs, the first cost of laying roads by this system is given as slightly 
higher than for reinforced concrete roads laid in situ, viz., £1 is. 9^. as against 
19s. 8^. per yard, but over a period of years, as is shown by a comparative 
table, it is anticipated that the lower cost of repairs will more than counter- 
balance this and show a saving. 

The experiment has now been in progress for three months, and Mr. Shellard 
states that the section is wearing well. If satisfactory results are obtained after 
a fair length of time, the Council is to be recommended to lay further sections of 
roadway on the same principle. He expressed the opinion that he had no fear 
as regards the strength of the slabs and their abihty to bear heavy traffic ; the 
only doubt was whether they would become loose through rocking as traffic 
passed over them. Mr. Shellard's full paper will appear in a subsequent issue. 

146 



CDNSTDUCTIC^AL 
, ENGTNEXRING — ; 



CIRCULAR COLD STORAGE BUNKER. 




CIRCULAR COAL 

STORAGE BUNKER AT 

CHAPELTOWN, NEAR 

SHEFFIELD, 

FOR MESSRS. NEWTON 
CHAMBERS & CO., LTD. 

By R. STUBBS, A.M.C.T. 



The circular form of bunker, constructed in steel, has been in use for some years 
by its designers, The Coke Oven Construction Co., Ltd., who have built fifteen 
bunkers of this form, of capacities varying from 600 to 1200 tons. 




\'ll u ul I'lMSllLP IKnKLK. 



During the War they desired to erect another circular bunker in connection 
with work for Messrs. Newton Chambers & Co., Ltd., for which they were the 



147 



A'. ST U BBS. 



[CONCRETE 



mechanical engineers, but owing to the embargo on steel another material had to 
be found, and they entrusted the design of a circular bunker in reinforced concrete 
to the Trussed Concrete Steel Co., Ltd. 

The most striking feature of this bunker to an experienced engineer is the 
extremely small amount of material used in its construction. Although the 
capacity of the bunker is 750 tons, the amount of concrete in the whole structure, 
including the bases and walls, is under 400 yards cube. This economy is apparent 
also in the amount of reinforcement, of which only about 21 tons was used. 

This saving of material was effected by eliminating bending stress wherever 
possible, and it is for this reason that the bunker was made circular. The hopper 
mouth, therefore, originally was conical, but at the request of the contractors, 
Messrs. Stuart's Granolithic Co., Ltd., was eventually altered to a twenty- four sided 
pyramid. Quite obviously the labour in forming the centering of this 
pyramid was considerable, but as this centering was used again for the top 




2*''2^ccL-:^n 




Det.^ils of Coal Storage Bi'xkkr. 

of the bunker, which, it will be noticed, is in the form of the frustrum of a 
twenty-four sided pyramid, the cost per 3"ard super was relatively low. Sur- 
mounting the hopper itself is a motor house in which the machinery for operating 
the inclined elevator is housed ; the material is conveyed to the bunker from the 
washery by this elevator, which is clearly shown in the accompanying illustration. 
At one side of the bunker the roadway runs on a le\-el approximately 12 ft. above 
the floor level of the lower house ; this house has been formed by filling in between 
the concrete columns with a reinforced concrete slab. 

The details of the reinforcement were designed by the Trussed Concrete Steel 
Co., Ltd. It is interesting to note, however, that the circular rings to the hopper 
mouth consisted of f in. diameter round rods, suitably lapped at their junctions, 
the laps in adjacent rings being, of course, staggered, while the hanging steel, i.e., 
the steel which was placed for the purpose of hanging the hopper mouth up to 
the main beam, consisted of | in. Kahn Rib bars. In several other instances, 
too, the combination of round rods and. Rib bars has been employed, each in 
the position most suited to its particular merits.* 



148 



\E 



CONSTBUCnoyAL 
ENGTNEERING — ; 



.4 700-rOX GRAVEL HOPPER. 



m 




'J"hi CoMii.tTiD Hopper. 



A 700-TON GRAVEL HOPPER. 

By V. ELMONT, B.Sc. 
The hopper described in the following lines presents some special features in 
so far as it is built 350 yards from the shore at a place where the depth of the 
water is 15 ft., and is designed as a com.bination of reinforced concrete and timber 
which has proved to be eminently efficient and economical. 

As illustrated in Fig. i, the gravel is transported from land to the hopper 
by means of buckets travelling on a cableway supported bv a special framework 




Showing Uischargi. oi Cirwi i. TiiKotr.u Srotr. 



149 



V. ELMONT. 



[QQNCROEJ 




Fig. 3. Showing Supports for Cablewav. 




Fig. 4. Details of Construction. 



150 



{&^^E^N^^ ^ 700-TON GRAVEL HOPPER. 

on top of the hopper and towers erected in the sea between the crushing and 
screening plant on the shore and the hopper. 

The storage capacity was made 700 tons, that is somewhat larger than twice 
the dead weight of the small steamers into which the gravel is discharged. 

In Fig. 3 will be seen one of these vessels lying alongside, ready to receive 
its load after the movable spouts have been swung into position. The process 
of filling the holds takes about 15 to 20 minutes. Fig. 2 depicts one of the spouts 
through which gravel is just being poured into the boat. 

The foundation for the hopper consists of six heavy concrete piers cast around 
clusters of wooden piles (see Fig. 4). About 6 ft. 6 in. above the water line 
the piers are interbraced by a reinforced concrete floor system. Each of them 
carries a 31 in. X 31 in. concrete column, stiffened by diagonal bracing. 
The column capitals are hollow and form the hoppered bottom of the super- 
structure whose walls are built entirely in wood. The supports for the cableway 
over the hopper are also formed by a timber construction as will be realised 
from Figs, i and 3. 

The columns are spaced 16 ft. 5 in. centre to centre and their height measured 
to the top of the capital is 26 ft. 7 in. ; above this level are placed the 10 ft. 4 in. 
high wooden hopper walls. 

The design and construction of this novel engineering structure, which was 
built near Copenhagen, are the work of the Northern Engineering Company 
" Cyclone," Ltd., Copenhagen, whose managing director, Mr. K. Hojgaard, is 
the originator of the plans. 

MEMORANDA. 

Reconstructing a Railway Viaduct. — Some interesting reconstruction work on a 
three-span continuous beam railway viaduct on the Sul Espirito Santo (Brazil) line 
of the Leopoldina Railway Company was given by Mr. F. W. Adolpli' Handman in a 
Paper before the Institute of Civil Engineers. The old girder was 197 ft. long, of the 
steel-lattice deck type, supported by masonry abutments and two trestles spaced 65 
ft. 8 in. between centres. The gradient on the viaduct was 3 per cent. Calculations 
revealed that the girder and trestles were inadequate to carry a contemplated increase 
of live load, and it was decided to reconstruct the trestles and to use three whole-plate 
deck-girders of 65 ft. 8 in. span each, the weight of each girder being 38 tons. The 
steel trestles, being inadequate as such, were encased in concrete. Particulars of the 
concrete used and the special methods of depositing were gi\-en by the author, who 
also described the method of placing the girders in detail, the advantages claimed being 
that — (i) No falsework was employed. (2) The only plant required were four 
50-ton ship's hydraulic jacks, two ordinary 20-ton wagon bogies and an oxy-acetylene 
apparatus for cutting steel. (3) 'I'hc substitution was carried out without interrup- 
tion to the ordinary passenger traffic, the interval between trains being 24 hours. 

Each complete span was riveted up at a convenient siding about two miles away, 
and run into position over the old span on two 20-ton bogie trucks. By means of 
wooden cribs and hydraulic jacks, the girder was lowered to rail-level. The end sway 
braces and laterals of the okl girder were then cut away bv means of the oxy-acetylene 
apparatus, and the new girder was supported by cribs directly on the abutments or 
piers. The continuous girder was cut completely through over the pier, the two sec- 
tions being slid outwards on special guides, the new girder being then lowered into 
place and the track fixed. Eacli girder was placed in a similar manner, and in each 
case witliiu the iillnttcd tune. 

Concrete Brine Troughs. — In order to protect the steel railway bridges from liie 
damage done to tliem by the brine from refrigerator cars, a narrow concrete trough, 
placed midway between the rails and designed to catch the fluid, is being installed 
on all steel bridges of a Michigan railroad. Concrete is unalfected by salt solutions. 
— American Architect. 

C 15T 



A HOUSE AT PETERSHAM. 



[CONCBETFJ 




HOUSE AT PETERSHAM. 

In our issue for February last year we gave an account of the steel-framed houses 
at Dormanstown, the town which is being built by Messrs. Dorman, Long & Co., 
for their employees. This method of construction, the steel frame covered with 
Hy-Rib expanded metal which is concreted to form the outer skin of the hollow 
wall, while the inner leaf is formed with breeze blocks, has proved so successful 
that it is being used in all parts of the country. This method of building has now 
taken on the name of " Dorlonco." We illustrate this month {see Frontispiece) one 
of its most delightful achievements, a detached house at Petersham, Surrey. 
This house, which stands with its garage adjoining, is situated on the borders 
of Richmond Park. The district abounds in beautiful houses var\'ing in age 
from 100 to 150 years with which this new erection will be in perfect harmony. 
The embellishments are few, and the decorative features scanty, 3'et, because 
the proportions are so good and because the ornament has been detailed with the 
utmost care, the result is so absolutely satisfactory. Note, for example, how the 
elevation gains by deviation from perfect symmetry, but it does so because the 
shutters of the sash windows balance the larger feature on the opposite side of 
the door. 

HOUSES AT WALSALL. 

Many local authorities in various parts of the country, finding that contrac- 
tors' tenders are too high for acceptance, have decided to undertake the erection 
of their houses by means of direct labour, thus eliminating the contractor and 
saving his profits. Where such authorities are willing and able to give adequate 
safeguards, the Ministry of Health are willing to give their sanction to this arrange- 
ment. Where the houses are to be built of concrete the problem for the local 
authorit}/ is an easier one, since, presuming the aggregate to be on or near the 
site, the amount of material to be ordered and handled is less than in the case of 
a brick scheme. At Walsall, in Staffordshire, most of the houses in the Corpora- 
tion's housing scheme are concrete. The town is situated near to Birmingham, 
where the housing shortage is acute, and the Corporation's scheme includes 450 
houses, most of which are to be erected on one large site which stands high 
up on gravel soil on the north side of the town. The site has been laid out 
in such a manner that the density of the houses is low, about 9 to the acre, 
so that the Council's scheme will contrast very favourably with the adjoining 
overcrowded property. Each house has its garden and provision is made for 
open spaces and playgrounds. Attention has been drawn, in discussing former 
schemes, to the enormously enhanced amenities which are provided by most of 
the Government housing schemes, and in view of the amount of criticism to which 

152 







i^ 



1 



CONSTKMCTlCfsA 
EMGITVEERING 



aD 



HOUSES AT WALSALL 



these schemes are sometimes subjected, it is only fair to point out that, even if in 
many cases the accommodation in the houses themselves leaves much to be desired, 
the iong rows of sunless houses, overcrowded upon each other, with only the 
smallest and filthiest back-yard, is indeed a thing of the past. 




"•1 



I'ig. 2. A CuiiiiJlclL-il lau ut Huuso. 

Houses at Walsall. 

Workhas-so far Incn Ixgun on i2o houses, and the job has been very thoroughly 
organised so as to economise in labour by Mr. J. Taylor, the Borough Engineer 
and Surveyor. Light railways have been laid to move material, and the Counril 
are erecting their own joinery and machine shops. Twenty-four houses are 
actually completed, the majority of which are of concrete block construction. 
The blocks arc made on the site with two ^2 in. Winget standard machines which 

C2 153 



HOUSES AT WALSALL. 



ICONCBETEJ 



are served by one chain-spade concrete mixer. This machine is able to make all 
the blocks required, of whatever shape. The construction adopted is a continu- 
ous cavity system, the outer leaf is 3 in. in thickness and is made of sand and gravel 
aggregate with which is mixed a small quantity of lighter aggregate obtained from 
the Corporation's sewage farm. The inside lining is 4I in. thick and is composed 
of equal parts of sand and fine ashes. It is to be regretted that the blocks were 
made with a rock face; we have had on former occasions to deplore this attempt 
to imitate stonework ; a smooth-faced block, or one on which the face was brushed 




Fig. 3. Houses in Course of Erectiou. 

over while still green to show the pleasant colour and texture of the aggregate 
would, in our opinion, have been a more successful treatment. Fig. i shows a 
corner block of two houses ; the grouping of the gables with the low sweep of roof 
in the centre is very satisfactory. In Fig. 2 is seen a house of simpler outline 
with a lower pitched roof. 

About half the houses on the site are of the parlour type. Fortunately for 
the Council, owing to the favourable price at which they have been able to build, 
the original standards of the Ministry of Health have been adhered to ; thus the 
living-rooms are the full 180 ft. super, instead of the reduced 160 which has now 
become the standard in parlour houses. Similarly, throughout, the sizes are 
generous, and the little extra fittings which help so much in the subsequent main- 
tenance of the house have not been eliminated at the tender stage. Thus the 
living-room is provided with a large cupboard which, with two drawers and a table 
top, serves as a sideboard. A hot airing cupboard is also provided. Electric 
light is installed throughout complete with all fittings and is charged for at a 
fixed weekly price per lamp. The houses that are occupied are proving extremely 
satisfactory ; there are no cases of dampness or of condensation. The price of the 
" B " type house has so far worked out at £837 55. per house, but this already low 
figure includes paths and the boundary wall, and it will be observed from the 
illustrations that this wall is executed in an unusually substantial manner. 

The whole scheme from its inception has been carried out by the Borough 
Surveyor with the aid of a staff of which Mr. W. H. Booth is the chief architectural 
assistant and Mr. S. G. Wilson the Clerk of Works. 

154 



J, constructional!! 

A ENGINEERING — J 



CONCRETE HOUSES IN AMERICA. 




CONCRETE HOUSES 
IN AMERICA. 



It is perhaps as unwise to generalise about a country's architecture after perusing its 
arcliitectural pubHcations, as it is to assess its national characteristics from a few 
inhabitants who may visit these shores. The first impulse, however, after turning 
over pages of Concrete Houses, is one of admiration at the comprehensive and progressive 
manner in which the problem of building in concrete so that the material shall be used 
to its best advantage, both practically and aestheticall}-, has been, and is being, 
approached. 

Concrete Houses * is published by the Concrete-Cement Age Publishing Compan}-, 
Detroit, and contains, for the most part, articles that have appeared in the monthly 
publication Concrete. A statement of the difficulty that has to be met, and which is 
common to both England and America, is made at the outset so succinctly as to justify 
a somewhat lengthy quotation. " It is the outstanding fault of numerous houses of 
concrete that they are both uneconomical and unconvincing from an architectural 
standpoint, because they are frame houses or brick houses masquerading in another 
radically different material. 

" When concrete is to be used, the designer should think in terms of concrete from 
footing to parapet. . . . Do architects and builders, as a class, never feel the need of 
new fields to conquer ? " Whether or no they feel the need, it would seem from the 
publication under consideration that new fields have been conquered ; it must be 
presumed, therefore, that such conquests are all too rare. 

The work of Mr. Irving J. Gill is not unknown in England. Without a doubt he is 
one of the conquerors, for he realises the essential qualities of the material, and, bearing 
these in mind, produces a design which is both logical and beautiful : in Fig. i, which 
shows a portion of a house from his design, the plasticity of the material is felt in the 
broad simple masses, and in the gently-rounded surfaces. Architects so often appear 
to be archaeologists or ignoramuses, so that their work is either the dead bones of the 
past dressed in new shrouds, or the illiterate utterings of those who know nothing of 
architectural tradition or forms. If the best results are to be obtained with concrete 
a mean between these extremes must be reached. Scholarship and imagination are 
requisite qualities. 

In England the most usual form of concrete construction is the concrete block. 
This is not so in .\merica. The volume contains more examples of monolithic work 
than of any other form of construction, much of this, as has been indicated, is of a 
remarkably higii quality. Where, however, the mechanical element predominates, 
the results are less satisfactory. Colonies of " poured " houses, identical in every 
respect, suggest a devastating monotony that it were well not to perpetuate. Fig. 3 
gives kn idea of the method by which this type of house is built. The forms consist of 
structural steel ciiannels in standard sizes, with holes so located that they can be 

♦ Concrete Houses: how they were built. By Harvey J. Whipple. 

155 



CONCRETE HOUSES IN AMERICA. 



[CONCRETE] 



locked together securely by means of clips and wedges. The really essential feature of 
these forms is the string course detail wliich forms a 2-in. projection at each floor, and 
forms the foundation on which the shuttering for the next floor is placed. The houses 
are built of concrete throughout, and the walls are solid ; the customary cavity is 
formed on the inside between the concrete and the plastering, which is fixed to studding. 
Fig. 2 shows the houses completed. 

Another frequently-used system of construction appears to be by means of pre- 
cast members. An extremely interesting example of this method of building occurs at 
a settlement known as Forest Hill Gardens. Fig. 4 gives an idea of the possible scope 
of this method, which has hitherto been the subject of only tentative experiments in 
England. The illustration suggests a mediaeval motif adopted to modern requirements: 




Fig. I. A Conxrete House i>j California. 

.4 rchitect : Irving J. Gill. 

the general arrangement and grouping certainly recall such towns as Rothenburg, but 
it is indeed no imitation. The whole work of building the settlement was carried out on 
modern manufacturing lines. The pre-cast members were made in factories. " From 
the casting-shed or head-house an overhead electric crane runs out through the storage 
yard, where wall, floor, and other sections are stacked ready for transportation on 
small cars running over an industrial railroad to the building site." The entire process 
from manufacture to erection seems to involve only three handlings. The walls 
between the pre-cast members are in many cases filled in with brick-work. Much of 

156 



>, CONSTPUCTIONAU 
t^ENGl>XERlNG ^-. 



CONCRETE HOUSES IX AMERICA 



the aggregate for the concrete is composed of broken-roof tile, so that the colour and 
texture of the whole must be very beautiful. The architect is Mr. Grosvenor Atterbury. 
A surprising fact about American work is the little precaution that seems to be 
taken against condensation. The usual method of dealing with the monolithic house 
has already been explained. The hollow wall seems to be regarded almost as a novelty. 
There would seem to be no example of the vertical sheet damp-proof course, although 
a section is shown of a monolithic wall which contains a porous block in the centre. 




Group of Monolithic Coscrete Houses. 




i-'ic. 3. Monolithic Concrete House. 

* In England wc are apt to allude witli much frequency to our bureaucratic metliods, 
and accuse them of liampering all progressive enterprises. It woukl appear that in 
one respect, at least, tlic English designer is less liampered than tlic American, by the 
passing of the Town Planning Act of ign}. Restrictive bye-laws liavc been rendered 
temporarily innocuoug, and this has enabled work to be carried out in many districts 
that would otherwise have been impossible. Tlie American arcliitcct does not appear 

157 



CONCRETE HOUSES IN AMERICA. 



[0:)NCBETEJ 



to be so favoured, and but little discrimination appears to be made between the require- 
ments imposed for the concrete factory or the concrete cottage, the entire structure 
in the latter case weighing perhaps only some 200 tons. 

Reference has frequently been made in this Journal to concrete surfaces. It is, 
perhaps, in these more than in any other detail that American work excels. The 
volume contains many illustrations of various surface treatments, including subsidiary 
building ornaments, such as wall fountains, garden ornaments, and the like. It would 
indeed be no exaggeration to state that this volume should be in the hands of all archi- 
tects and designers who are interested in domestic architecture, and if, perchance, 
some of them are as yet not awake to the problems of the day, or to the potentialities 
of concrete, the book may throw light where it be most needed. 




Fig. 4. Forest Hill Gardens. 



158 




THE CONCRETE INSTITUTE. 



THE CONCRETE 
INSTITUTE. 

MONTHLY NOTES. 

Bv the SECRETARY 



COUNCIL AND COMMITTEE MEETINGS FOR MARCH AND APRIL. 



March 3rd. R.C. Practice Standing Committee, at 4 p.m. 
Science Standing Committee, at 5.30 p.m. 
loth. Literature Standing Committee, at 5.30 p.m. 
17th. Finance and General Purposes Committee, at 5.30 p.m. 
,, 31st. Council, at 5.30 p.m. , at c 

Ordinary General Meeting, at 7.30 p.m Paper by Mr. Sven 
Bylander. M.C.I., entitled " Stresses in Structural Steel. 
April 7th. R.C' Practice Standing Committee, at 4 p.m. 
Science Standing Committee, at 5.30 p.m. 
14th. Literature Standing Committee, at 5.30 p.m. 
2ist. Finance and General Purposes Committee, at 5.30 p.m. 

',', 28th. Council, at 5.30 p.m. u -n ^ t r t .. 

Ordinary General Meeting, at 7.30 p.m. Paper by 1 rot. i^ . C. Lea, 
D.Sc," entitled " The Elastic Modulus of Concrete. 

RECENT ELECTIONS INTO THE INSTITUTE. 

Members :— Bourne, Wilfrid Augustin Ranulph. 

?l\STON. William Cecil. 
Ellis, Philip. 
Glock, Arthur James. 
Green. Douglas Harold. 
HoBBS, Arthur Ernest. 
HoLBROW, Alfred Ernest. 
Jardine, Henry Stringer. 
Kersey, Alfred Thomas John. 
Latham, Daniel John. 
Macklev, John Thomas. 
Mitchell, George Arthur. 
, Shingleton, Leslie. 

Thain, Thomas Edward. 

Cramer, Wilham (passed E.xamination). 

Harrison, John Lawrence Eagle (from Student). 

Hi'NTLEY, .\rthuj- Geoffrey. 

LooNBA. Ram Lall. 

Morton, Harry (Graduate ; passed Examination for A.-M.). 

O'CoNNELL. Terence Joseph (passed Examinatu)n). 

RouGHAN, fames Joseph (passed Examination). 

Shore. Albert William (passed Examination). 



Associate Members 



159 



THE CONCRETE INSTITUTE. [CONCRETE] 



Graduates : — Cloke, Cecil Jesse Witney. 

Crowther, Fred Sefton (passed Examination). 

Jones, Ernest. 

ScHOFiELD, Reginald William (passed Examination). 

Students : — Berry, Cecil Vernon. 

Clayton, Arthur John Hamblin. 

BUILDING TRADES' EXHIBITION, OLYMPIA. April 12lh to 26th, 1921. 

The Institute hopes to make arrangements for some lectures at the above 
Exhibition, full details of which will be published later. 

NOTICE TO INVENTORS, PATENTEES, AND MAKERS OF SHUTTERING FOX 

CONCRETE WALLS. 

The Concrete Institute is preparing a list of various kinds of shuttering for 
Concrete Walls ; and Inventors. Patentees and Makers of such kinds of shutter- 
ing are requested to send particulars to the Secretary, Concrete Institute, 296, 
Denison House, Vauxhall Bridge Road, Westminster, S.W.i, for inclusion in the 
list. 

Descriptions should be as brief as possible, and the particulars will be edited, 
with a view to the deletion of all extravagant claims and all statements derogatory 
to the products of the vendor's competitors. 

Illustrations can be printed alongside the descriptions, provided that blocks 
are supplied at the same time. 

NOTICE TO MAKERS OF WATERPROOFING COMPOUNDS. 

The Concrete Institute are enquiring into the claims made for various water- 
proofing compounds for concrete, and makers of such compounds are requested 
to send to the Secretary, Concrete Institute, 296, Denison House, Vauxhall Bridge 
Road, Westminster, S.W.i, a paragraph giving brief particulars of their com- 
pounds for publication. 

CONCRETE AGGREGATES {continued). 

SUPPLEMENTARY. 

(i8a) Chichester (Sussex). — 

General description : Flinty gravel. 

Source and Locality : Pound Farm, Chichester. 

How obtained : Digging. 

From whom obtained: The Pound Farm Gravel Company. 

/5 available quantity limited ? No. 

Present maximum output per day : 50 tons. 

Transport facilities : Road and Rail ; Water transport could be arranged. 

Is there any provision at or near source for washing or crushing ? For washing. 

Price at place of delivery : 8s. 6d. per ton in the Pit ; ids. 6d. per ton on Rail. 

/5 composition uniform ? Yes, if required. 

Shape of particles : Angular. 

Size of particles : Any size from " sand " upwards, graded as required or 

mixed. 
General remarks : The material is washed clean, and is used locally for the 

better class Concrete work ; but the major portion is 

being delivered by road and rail for use elsewhere. It. 

is also much used for tar-spraying in the smaller sizes.. 

* See issues commencing with August, 1920. 
160 



f&^i;!g^N^ THE CONCRETE INSTITUTE. 

MAIN LIST. 
(33) Faringdon (Berkshire).— 

(i) General description : Pit gravel, (ii) Gravel and sand. 

Source and locality : Local pits. Local pits. 

How obtained : * ' Felling and digging. 

Is available quantity limited? Xo. No. 

Present maximum output per day : Small, but could be increased. (ii)Not 

known, but large supply. 
Transport facilities : One mile carting, thence by Rail, (ii) Horse and tractor 

or Rail. 
Is there any provision for washing or crushing at or near source ? No. (ii) No. 
Price per cub. yd., and where delivered : 3s. 6d.to4S. at Pit. (ii)3S. 6d. at Pit. 
/5 composition uniform ? Yes. (ii) Three classes. 

Kind of stone or coarse material : (ii) Limestone local and gravel stone. 
Kind of sand or fine material : (ii) Siliceous. 
Relative proportions of coarse and fine material: (ii) i to 2. 
Shape of particles : (ii) Angular as regards the large particles. 
Size of particles : approximate . 

percentage that needs crush- Almost ^o p.c. (ii) 12 in. to 3 in. downwards. 

ing to pass J in. screen' \ 

Impurities present : (ii) Small amount of clay. 
General remarks : (ii) Very commonly used, and ranks in the first class. 

* No information supplied. 

TESTS ON HIGH TENSION STEELS IN REINFORCED 
CONCRETE DESIGN. 

By H. KEMPTON DYSON. 

The following is an abstract from a Paper read at the Ninety-ninth Ordinary 
General Meeting of the Concrete Institute on Thursday, January 13ih, 1921. An 
interesting discussion followed upon the reading of the Paper. 

The tests describee in this Paper are the outcome of an agitation that has been pro- 
ceeding over a period which commenced some years previous to the war. 

Certain firms of reinforced concrete specialists had been selling special steels 
which they contended could be safely stressed to considerably more than ordinary 
mild steel. They had employed their reinforcements in works which they had designed, 
where they had adopted such higher stresses, but the then proposed regulations for 
reinforced concrete which were being formulated by the London County Council and 
submitted to the Local Government Board did not permit them to use such higher 
working stresses. This they considered to be unfair, and they protested vigorously 
to the various Technical Societies and in the Press. 

The Joint Committee on Reinforced Concrete conducted by the Royal Institute of 
British .Architects took notice of this contention in their Second Report and suggested 
that if stronger steel were used the allowable tensile stress might be taken at half the 
stress at the yield point of the steel, but in no case should it exceed 20,000 lb. per 
square inch. This, of course, should be compared with the figure of 16,000 lb. per 
square inch which thev advocated as the working stress on mild steel, having an 
ultimate tensile strengtii of 28-32 tons per square inch. 

The Concrete Institute was one of the chief bodies concerned with the criticism 
of the Regulations of the London County Council when they were in draft. They 
made the most suggestions for alteration, and their suggestions were largely adi)ptecl. 
They supported the contention of the specialist firms interested, and agreed witli what 
had already been advocated by the Britisli Joint Committee, in suggesting that for 
special steels, such as medium carbon steel and drawn steel wire, a working slre.ss of 
20,000 lb. per square inch should be permitted. 

The officials of the London County Council and the Local Government Boards 

161 



H. KEMPTON DYSON. [CDNCKETE] 

however, did not agree with this recommendation ; and the Regulations, as finaUy 
approved, permit only of the steel being stressed to 16,000 lb. per square inch, and 
moreover they provide that the steel shall conform to the qualit}' required by the 
British Standard Specification for steel for bridges and general building construction. 
This the firms interested considered to be grossly unfair by restricting proper improve- 
ment in engineering practice, and they protested to the Concrete Institute very strongly. 

They were told by the officials that if they could get the Engineering Standards 
Committee to make a specification specially relating to their steel, permitting a higher 
stress to be used, the thing would be automatically taken account of in the Regulations. 

On application, however, to the Engineering Standards Committee, tliey were 
rebuffed on the grounds that there was insufficient demand for their steel for it to be 
worth the while of the Engineering Standards Committee to draw up a special specifi- 
cation for such steels. 

Eventually, as a result of the agitation, the Concrete Institute decided to appoint 
a special Sub-Committee which should report to the Council and upon which all those 
commercially interested would be represented, together with certain professional 
members considered to take a somewhat independent view. 

This Sub-Committee was formed, and consisted of the following : — Messrs. J. F. 
Butler, H. Kempton Dyson, R. H. H. Stanger, B. Taylor, R. W. Vawdrey and T. A. 
Watson. The following were subsequently added to the Committee : — Messrs. A. L. 
Johnson, A. W. C. Shelf and H. R. White. 

The writer of this Paper was appointed Chairman, and explained what had 
occurred at the Joint Committee meeting at which the representative of the Engineering 
Standards Committee and the Institution of Civil Engineers had expressed the opinion 
(in which some other members of the Joint Committee concurred) that it would be 
desirable to endeavour to settle the controversy by means of tests, which would be 
conducted by some independent body, and therefore would not be open to the criticism 
that they were made by the firms interested in marketing special steel. The Committee 
came to the conclusion, therefore, that it was desirable to conduct such tests in order to 
determine if the claims were really justified. 

The specialist firms expressed their willingness to contribute to the costs of such 
tests. 

After considerable discussion, it was thought best to conduct a preliminary series 
of experiments, which would give data that might serve as sufficient evidence to con- 
vince engineers generally, and the authorities in particular, or would serve as a basis 
to devise other tests, which could be witnessed by official representatives. 

The discussion brought out certain opinions which it was desired to test, and two 
sets of experiments were considered necessary. 

The first set consisted of a number of slabs which were to be tested with a point 
load at the centre. These tests had for their object to show whether steels of higher 
tensile strength than mild steel could be employed to give a greater moment of resist- 
ance than mild steel, without undue cracking by reason of the extra extension resulting 
from the higher stress. These tests were such as not to test the shearing resistance of 
the concrete. 

The second series of tests were on beams in which the shearing resistance of the 
concrete was to be tested, it being thought by some that if special steels were used, 
which could be stressed higher than mild steel, the size would be correspondingly 
reduced, and with the diminution in the size of the reinforcement, the ratio of circum- 
ference to area would be increased, so that the adhesion would be similarly greater, 
and that this increased adhesion might reduce cracking, and so enable the concrete to 
resist greater diagonal tensile stresses, i.e., have a greater shearing resistance. In 
particular it was thought that where a number of drawn steel wires were employed 
the adhesion would be so much greater than where only a few bars of large diameter 
were used, that the concrete would not be cracked adjoining the supports, because 
the extra adhesion would enable the concrete to be stretched without cracking (an 
argument originally put forward by Monsieur Considere) so that the shearing resistance 
might be found to be thereby increased. 

Series of slabs and T beams were designed to meet these theoretical views. In the 
first series mild steel bars were disposed in the slabs to compare with the special steel 

162 



i 



g^Njn;|ucric^AL] TESTS ON HIGH TENSION STEELS. 



reinforcement. In the first case a slab was designed so that when the stress in the 
steel was 16,000 lb. per square inch the stress in the concrete would be approximately 
600 lb. 

In the second case the area of the steel was such as would develop 16,000 lb. per 
square inch, while the stress in the concrete was only about 550 lb. per square inch, 
that is to say, the area of steel provided was approximately twent3-sixteenths of the 
high tensile steels, the stress in the concrete being kept below the usual working stress 
of 600 lb. per square inch. 

The special steels on the market were found to belong to three tj-pes, namely, 
those of 

(i) Medium carbon steel, like " Indented " bars ; 
(2) Cold worked steels, such as twisted bars ; 

and (3) Drawn steel wire. 

It was thought by some members of the Committee that it might be necessary 
in order to develop the higher stresses when employing medium carbon steel to have a 
continuous mechanical bond, such as was provided by the " indented " bar ; but it 
had been found during the war that the shell-discard steel permitted to be used by the 
Government for reinforced concrete work conformed more or less to this category, in 
that it was a higher carbon steel than ordinary mild steel, and had generally a greater 
ultimate strength. Therefore a set of tests was decided upon wherein shell-discard 
steel was to be employed, such steel bars being supplied by the firm rolling the " in- 
dented " bars, with a view to their being of similar quality material— the results of the 
tests seem to indicate that the steel furnished was not what was required. In the 
slabs, at any rate, it was more in the nature of mild steel, that is to say, it 
was exceptionally good shell-discard steel, and unfortunately this part of the inquiry 
failed, in that the steel was not as intended. In the beam tests the steel was not really 
tested in tension, but only the resistance of concrete in shear. 

The steel was given free by the various specialist firms. 

Mr. Stanger, one of the members of the Committee, most kindly offered to test the 
specimens in his testing machine, if the specimens were made for him ; but difficulties 
were met with in making the test specimens near to Mr. Stanger's works and in devising 
a means of getting them into his testing room, so that eventually it was decided to make 
the tests in Manchester, because at Manchester College of Technology they had an 
equipment for testing beams in a vertical position, which it was thought would be 
somewhat better than horizontally, as would be the case in Mr. Stanger's machine, but 
the Committee decided they would avail themselves of Mr. Stanger's kind offer to test 
the specimens of steel bars. This procedure was followed. 

An estimate was obtained from a Manchester firm of contractors, namely, ISIessrs. 
Tinker and Young, for making the specimens on a vacant site adjoining the College of 
Technology. 

The concrete was made in what was supposed to be the ordinary average manner, 
of the ordinary quality employed in buildings, for which the working stress adopted 
would be 600 lb. per square inch. 

The Table, p. 164, gives the general data regarding the design of the test pieces. 
It shows working stresses under working loads. 

It was anticipated tliat the tests would show a factor of safety approaching 4, 
that is to say, that the breaking load would be four times the working load given in the 
table. The loads stated in the table include for the deadweight of tlie specimen itself. 

The detailed records of the tests indicate that the factor of safety shown for the 
slabs reinforced with mild steel rods was approximately 3-6, that is to say, the moment 
of resistance at rupture was 3-6 times the moment of resistance for which they were 
designed when the stress was 16,000 lb. per square inch. 

Tliis factor of safety of just under 4 has been evidenced in numerous tests on 
reinforced concrete beams, and we must therefore reckon that in practice we are really 
content with this factor of safety. 

The test records show tiiat if we arc content with the same factor of safety for high 
tensile steels, tlien it would be right to design (as compared witli the working stress of 
16,000 lb. for mild steel) for working stresses oif 22,000 lb. per s<iuare inch for medium 
carbon steel and 21.500 lb. per square incli for " twisted " steel bars, and 25,000 lb. 

163 



H. KEMPTON DYSON. 



iCDNCBETE] 



per square inch for drawn steel wire, of the respective qualities employed in these 
particular tests. 

As regards the question of the deflections being greater, consequently the cracks 
larger, the tests show that the deflections were certainly greater, because, of course, the 
loads sustained by the beams were bigger ; but the tests bring out quite clearly, as is 
shown by photographs, that in all cases the increased stress developed in the' steel 
did not result in larger cracks, but only in a greater number of cracks, therefore the 



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argument, that b}- using a higher stress the steel would be exposed more to corrosion, 
falls to the ground. 

As regards the tests on the T beams, the writer thinks that these failed to show 
any of the supposed advantage that there might be in the smaller sizes of reinforcement. 
That is to say, the test results do not appear to show an\- increased resistance to shear 
even when drawn steel wire was employed. The failure occurred very nearly as was 
originally estimated. 

164 



k^y^tSTi^^ TESTS ox HIGH TEXSIOX STEELS. 

The writer would like to add, however, some personal observations of his own, for 
which, it must be clearly understood, the Committee accept no responsibility. He 
hopes that these tests may be accepted as sufficient evidence by the Societies, London 
County Council and the Ministry of Health, to warrant the sanction of a higher working 
stress for special steels without putting the firms and others interested to further 
expense, because these tests have meant a considerable expense, both of money and of 
time and they appear to be pretty conclusive. 

The tests on the slabs bring out clearly certain points which have been noticed in 
other tests and serve to illustrate a point which the writer desires to emphasise. It 
has long been argued by practical exponents of reinforced concrete design that slabs, 
as commonly designed and constructed, are one of the strongest parts of reinforced 
concrete construction, and that as regards their compressive resistance, they are much 
stronger than theoretical calculations would indicate, that is to say that a much higher 
percentage of steel could be employed without failure of the concrete. Evidently, if 
this is so, the determination of the stresses in the concrete is in error. The primary 
difference is probably due to the efforts of certain academic engineer professors, who 
have studied the works of elasticians, and have for some decades advocated the design 
of beams for working stresses, such working stresses being reduced by dividing the 
ultimate strengths of the materials by a factor of safety, instead of following the 
procedure of the earlier engineers — practical men who did an enormous amount of 
construction and obtained their knowledge from actual experience ; such older engineers 
experimented to find the ultimate resistance of beams and other parts of structures, and 
then adopted as the working load for such members a load which was obtained by 
dividing the ultimate resistance by the factor of safety. It is very difficult to determine 
what are the real stresses in the material at intermediate stages in the loading of such 
tests as have here been described, but the conditions at the point of ultimate failure are 
more readily ascertained. 

It will be familiar to all students of reinforced concrete that in the formula? which 
are commonlv used there is a factor introduced called the modular ratio. This is 
supposed to be the ratio between the modulus of elasticity for the steel and the modulus 
of elasticity' for the concrete. The tests on these materials show that the modulus of 
the concrete is continually changing, getting less as the stress increases, whilst the 
modulus for the steel drops very considerably when the yield point is passed, and with 
cold worked steels there is no well-defined yield point, so that there is no well-defined 
modulus. It is really not necessary to introduce the modular ratio into the formula at 
all, and it is suggested that it would be far better to abandon this mysterious variable 
and calculate always for probable ultimate resistances of beams, and then divide the 
resistance bv the factor of safety, in order to obtain the working load. 

All oiir data regarding reinforced concrete beams are derived from tests, and we 
know very little about what happens at intermediate stages of loading as regards the 
real stresses in the beams, but we know something definite about the point of failure. 
If we make our calculations for the ultimate resistance, we shall have to abandon the 
triangular stress strain distribution for the compression in the concrete and adopt some 
such figure as an ellipse or a parabola. Personally, the writer favours the ellipse as a 
nearer approach to the truth. The fact that the stresses are distributed more like the 
ordinary ellipse in the compression area of the beam accounts for the fact that one can 
put much more than the usual percentage of steel in slabs or rectangular beams without 
causing failure of the compression. 

Tliese tests illustrate what other tests have done, that as the load increased, the 
cracks at the centre crept up higher and higher, until the stress passed beyond the yield 
point of the steel and the steel began to extend considerably. The crack then extended 
so high that the portion of concrete left to carry the compression was so small that the 
concrete had to be ruptured. In all these tests the steel was never broken. It was the 
concrete which failed, and yet by estimating an approximate lever arm, one can calcu- 
late that the stress in the steel was so great that it was the steel that really was the 
primary cause of failure. There was plenty of concrete to enable the steel to be stressed 
well hevond its yield point. The fact that the bars were well hooked at the ends 
probably enabled tiic yield point to be exceeded considerably, though it has been 
contended by some investigators in the past, who did not properly anchor their steel. 

165 



H. KEMPTON DYSON. [CONCRETE] 

that the yield point was the critical factor and that when the yield point was reached the 
beam was bound to collapse. By their argument, the factor of safety in reinforced 
concrete was about 2 to 2^, and consequently some engineers thought that in order to 
ensure a proper factor of safety of 4, a working stress of about 10,000 lb. per square 
inch on mild steel should be adopted. 

Of course the shifting of the neutral axis up towards the top of the beam is indicated 
by the ordinary theoretical formula? if only we remember that when the stress in the 
steel passes the yield point, the modulus in the steel drops very rapidly, while if the 
concrete is not failing the modulus is dropping much less rapidly, the result therefore 
being that the modular ratio decreases ; and if in the ordinary formulae we insert 
a lower value for the modular ratio, the position of the neutral axis is found to be much 
nearer the top of the beam. It seems to the writer a matter of importance to get a 
method of calculation which is precise from a mathematical point of view, yet is at the 
same time practical. It is a subject which he hopes to deal with again in a more 
detailed manner. 

DISCUSSION. 

The Chairman read a letter from Dr. Oscar Faber, O.B.E., etc. in which the writer referred to 
the fact that of course high tensile steel has been known to engineers these last ten years, and yet 
many of them had decided not to use it or, at least, not to stress it higher than mild steel for what he, 
the writer, considered good reasons. He was aware that it had been used in several places where there 
was vibration without serious disadvantage, but the steel used in those cases was an expensive alloy 
and the cost of same would have put it out of court for use as reinforcement. There was a two-fold 
danger with high tension steel. 

(i) The writer's experience, and that of other engineers, was that that quality of high tensile steel 
which has been commonly a\"ailable for reinforcing has only been bent cold with considerable risk 
of fracture. 

{2) High tensile steel of the quality available for reinforcing is much more liable to become crystal- 
line and brittle witli vibration incidental to many types of structure than ordinary mild steel. 

It would, therefore, appear to be a matter of common precaution to ask for a higher factor of 
safety on this material to provide against this risk of collapse due to the material becoming crystalline. 
Dr. Faber stated his own attitude in the matter has been — while not objecting to the use of high tensile 
steel — strongly to resist stressing it to higher stresses than he would be willing to use for mild steel. 

The writer was of course aware of tests made and the results obtained, and also of the fact that 
excellent steels are manufactured to-day, which give liigher tensile stresses without loss of ductihty, 
but such steels are dearer than commercial mild steel. When we confine our attention to the actual 
liigh tensile steels which have been used by tirms selling patent bars, it is undeniable that their use 
has been accompanied by indications that tlieir behaviour, when bent cold, and subsequently, was 
likely to involve some risk as compared with the use of mild steel. Dr. Faber went on to say : " Per- 
sonally, I should consider the well-being of the community would suffer in a risk of collapse of a greater 
proportion of concrete buildings than at present if the use of high tensile steel is permitted without 
greater safeguards to the public as to quality — particularly ductility — than is asked for at present 
with mild steel." The writer said he was, of course, not unsympathetic to the use of better materials 
in the future and taking full advantage of their properties. 

In the last paragraph of his letter Dr. Faber referred to those steels in which additional strength 
is obtained by a twisting or other kinds of treatment other than chemical compositions, and he said 
that the raising of the yield point in these bars is lost when they are heated to a dull red heat. 

Other disadvantages to high tensile steel are to be foimd in the greater number or size of hair 
cracks which will be produced on the tension side of members. 

Mr. A. W. C. Shelf said he was an advocate of a higher stress being taken for high tension steels. 
He was not an advocate of a high carbon steel, because you were more likely to get crystallisation 
with a high carbon steel than with a cold worked steel. But a high tensile steel, a cold worked steel 
more especiallv, he was a strong advocate of. He was also in favour of high tensile steel as wire, 
but that might work out slightly uncommercial at the finish. He agreed with Mr. Dyson that the 
modulus of elasticitv was more or less a theoretical bogey. With regard to some remarks in Dr. 
Faber's letter, the subject of cold worked steel and twisted bars was not in the state that it was 
when he (the speaker) took it up twelve years ago. At that time there had been tremendous 
failures. The application of a square twisted bar was entirely- wrong for reinforced concrete. By cold 
twisting a round bar you got a higher efficiency than with a square bar. This question of cold twisting 
had become a scientific study ; up to a certain point the process built up the structure of the steel, 
but beyond that point the particles were cracked or fractured by it. For twelve years now buildings 
had been going up in this country where there were stresses of 25,000 lb. on the square inch of steel, 
and there had been no failures ; in fact there were records to prove that everything had been highly 
satisfactory. The only thing you were likely to get with bars of this kind was, perhaps, more numerous 
hair cracks instead of the lesser number of cracks vou got with a mild steel. 

Mr. J. F. Butler, A.C.G.I., A.M.Inst.C.E., said the tests had brought out results, as far as steel wire 
was concerned at any rate, which had long been kno\\"n to the manufacturers of steel wire reinforcement. 
He was glad of this official confirmation — because he hoped it would be considered as an official con- 
firmation by the Concrete Institute. He thought Mr. Dyson had been himself surprised at the results 
of the tests, but those who had been manufacturing were not surprised, because they had made similar 
tests themselves and had got exactly similar results. It was customary for manufacturers of steel wire 

166 



^^■^^^n^ TESTS ON HIGH TENSION STEELS. 



reinforcement to stress up to 25,000 lb. That stress was regularly used outside the area of the London 
Covuity Council and those areas which had followed the London County Council's regulations ; aiid in 
one or two cases it had been used inside the London County Council's area. Dr. Faber in his letter 
had brought forward the old bogey that slabs reinforced with high tensile material were objectionable, 
because of the cracks. It used to be said that you got larger cracks, but these tests proved that the 
cracks were not larger. They might be larger in total extent because there were a larger number of 
them, but he thought a large number of small cracks was not so objectionable as a small nimiber of 
large cracks. 

Mr. H. R. White said that he represented an American firm interested in the sale of steel bars and 
wires, and that when he informed his principals that these tests were to be made they had expressed 
surprise that further tests were necessary. They felt that tests had been done to death ; but he had 
pointed out that the authorities here were ven,' conservative and put no faith in tests made by manu- 
facturers, or in tests made abroad, even if these were made by technical institutions with no commercial 
interests to serve. Tests made abroad on high tensile wire, had hitherto been made on fabrics only. 
In actual practice wire was likely always to be used in a fabric, and therein were several advantages. 
The fabric ensured that the amount of reinforcement specified was there ; but if you used bars of any 
kind they might be displaced, or, if the supervision was not what it should be, they might not be there 
at all. But any one could see whether a fabric was there. 

Mr. B. Taylor, M. Saliord Eng, Assn., said he had been interested in tests carried out for a period 
of about fifteen years — from tlie first instigation of reinforced concrete. These had been both bar and 
slab tests, and, like the tests described that evening, the}' had all gone to prove that the basis of the 
old R.I.B.A. formula, under which work was being done to-day, and which was in principle incorporated 
in the London County Council Regulations, was quite right ; but that modification was needed in details. 
As to Dr. Faber's remarks about high tension steel being brittle and uncertain — for that was what it 
amoimted to — they referred more to the shell steel that had been about during the war. This was a 
very high carbon steel. It had high tensile strength and a ver\' small elongation ; what was needed 
was a medium carbon steel with medium elongation. He thought that for columns high carbon or high 
tension steel did not give the same advantages as for beams. Unless it became recognised as an every- 
day commodity, as mild steel had become, its cost would very often take away all its advantages ; so 
long as it was something special it would command a special price. But this matter would right itself 
if medium carbon or high tension steel was recognised by engineers to have decided advantages, and the 
rolling mills put dowii plant and laid themselves out for making it by mechanical process. With regard 
to steel wire the material was consolidated by the drawing ; its density was intensified, and it was this 
fact that gave it its mechanical strength. It was quite usual to stress it to 25,000 lb. 

Mr. P. G. Bowie said he thought the question rested mainly on the structures that had been put up. 
The whole thing was so variable you could not compare one case with another. If you took, say, 
25,000 lb. with wire, what moments and that sort of thing did you take ? 

Mr. Ewart S. Andrews, B.Sc. (Eng.), M.C.I., said although he thought there were certain 
safeguards to be kept in mincl in the use of high tension steel, he had always opposed any attempt to 
prevent its use. He objected on principle to any material being ruled out of court merely by a regulation 
in the absence of any definite reason for ruling it out. The principal objection raised against high 
tension steel was that it was brittle. But it need not be brittle, though, if we were to use it, great care 
was needed in manufacture and supervision. He had had an experience of high tension steel which 
was stressed up to 21 tons to the square inch and was perfectly satisfactory, and each article made from 
that steel was put to a second test of, he thought, 32 tons to the square inch ; and he had not the 
slightest doubt that, if the people interested in the production of steel bars or steel beams would take 
the trouble, a medium carbon steel could be produced with an ultimate strength of 37 to 40 tons per 
square inch — with the necessary tension and ductility. If the steel was not brittle he saw no reason 
why it should not be used in concrete, or why, when so used, it should not be used to a stress commen- 
surate with its yield point. If the present document did not convince the authorities, the next thing 
he would like to see would be tests to show whether the same comparative effect was got by drop tests 
on the slabs. Without attempting to prophesy, he thought that slabs made with the same high tensile 
steel as in these experiments would show as well imder the drop test as with the static test. A more 
difficult point was as to what would happen if there were fire in the building and the steel was heated 
up to its critical temperature and softened. This was a real danger, but it was quite easy to make 
provision for the stabilit}- of a building to be reconsidered if a fire had taken place in it. A point had 
been raised with regard to ultimate strength and working stress. In cases where our existing knowledge 
did not enable us to proceed; actually on theoretical calculations, he was quite willing to be guided entirely 
by tests — in fact it would be foolish to do anything else. But directly you started basing your work 
entirely on tests you never knew to what extent the test that you were being guided by fitted in with 
the conditions you were designing for. Anutlier point was that every time you went past the yield point 
of steel you altered its character, until ultimately you could make it quite brittle ; so that the same 
conditions did not linld after the yield point had been reached. 

Mr. W. J. Pickering said he was not clear why modem engineering practice had no4 been followed 
in ascertaining the tiring value of the different kinds of steel. This was a common practice in the 
north of England. Another thing was, why should we perpetually test concrete in tension and not in 
compression ? It was obvious from these tests that it was the compression which was of account. 

Mr. E. Lawrence Hall said that even in London he had come across cases where 25,000 lb. had been 
' l.iitiiid to lie u-t'(l, :iii(l liad actually been allowed. 

Mr. P. J. Black, Distric t Surveyor for Wandsworth l-'ast, said that of course work done in reinforced 
concrete in London was not necessarily done under the Reinforced Concrete Regulations. As to the 
modulus of elasticity, was it not tlie fact tliat .\merica, and (Icrmany before the war — and possibly 
now — had a different Naiuc fioiii ours? 

Mr. Allan Graham, A.R.LB.A., said he disagreed with a remark that had been made that high carbon 
steel was not suitable for colunuis. A great many reinforced colunms had eccentricity, and the high 
1 arbon steel would be of great assistance in reducing the amount of steel required, or reducing the size 
D X67 



H. KEMPTON DYSON. [CONCRETE] 

of the concrete core. The tests had demonstrated conckisively that at any rate steel wire was able to do 
its work. 

The Chairman, Mr. E. Fiander Etchclls, said he would hke to remove one or two false impressions ; 
one was as to the Kegnlations. These were not made by any single individual whatsoever ; they were 
made by the County Council after holding many meetings. The Council was guided by its officers, 
who in turn had consulted expert conunittees. Regulations which were come to by many minds and 
not by any individual mind, must come to a centre of gravity of opinion rather than be ultra- 
progressive or ultra-conservative. But the purpose of having Regulations was so that these could 
be altered more easily from time to time than an Act of Parliament could be. When the time was 
ripe, possibly before it was ripe, the necessary steps would be taken for the amendment of the Regu- 
lations. One speaker had said that we should not be prevented from using high tension steel from the 
fear that after a fire the building would not be so strong as it had been ^jreviously. But this con- 
sideration had not weighed with anyone he was personally acquainted with. Fire had been regarded 
as an accident to the building, and not as something which should govern the construction of other 
buildings. Another matter was that there had been no ruling out of high tension steel by those who 
made the Regulations — it was specially provided for. 1 here was one matter in which he was 
really very sympathetic with the authorities, and he believed his audience would be sympathetic 
too when he explained the point. In the case of reinforced concrete there was a question whether 
the formuljB for construction should be based on the elastic limit, the yield point or the ultimate 
stress. There were these three methods, and whichever one you selected you might be sure the partisans 
of the other two methods would trounce you. Mr. Dyson had expressed the hope in his paper that the 
tests might be accepted as sufficient evidence to warrant the sanction of a higher working stress for 
special steels. But there had been no representatives of building authorities or Government Depart- 
ments present, nor of the other technical institutions that must be consulted. Another point was that 
Mr. Dyson had suggested we should abolish the modular ratio and base our calculations on the lever 
arm, because the modular ratio was a little uncertain ; but he had gone on to say that the last reading 
always destroyed the last crack which told where the lever arm was. We should never reach perfection. 
Mr. Dyson then replied to the discussion. Dr. Faber, he said, talked about shock, and the fact 
that bars had broken off short when being bent. That happened with mild steel as he (the speaker) 
had seen many a time ; it depended on the kind of bending machine for one thing. Of course there were 
brittle bars ; of shell discard bars some were rotten, some extremely good. He had had some tests 
carried out that showed that shell steel had greater ductility than the ordinary mild steel of pre-war 
days. Some of the mild steel sold in the form of ordinary rounds was really cold worked steel. He 
knew one rolling mills where, when the smaller bars were rolled, the steel got so cold that it was really 
cold worked steel ; if you tested the bars made there from the same lot of steel the bigger bars would be 
found to have less ultimate strength than the smaller bars. The arguments about what happened 
when you shocked a piece of cold worked steel made him think such critics had never been in a rolling 
mill. Just to illustrate his point he would like to tell them of a visit he had paid to one of the largest 
rolling mills in the country some time ago, when there happened to be a strike on, so that he had 
the opportunity of seeing a good deal more than usual. Some very large section I-beams had 
been stacked while hot. Long lengths had been laid on the flat (on their sides) on top of short 
lengths ; so that there was a pile of short lengths several feet high, and long lengths laid on them with 
ends overhanging. The long beams had been laid there when red hot, and the ends had bent right dowTi 
— a tremendous bend. Did any one think those beams were put into the melting pot again ? No. 
Round the corner were presses which all rolling mills had for straightening steel beams. This straighten- 
ing is done cold ; that is the steel is cold worked, and enormously so when such great bends are taken 
out as in the large beams referred to. Yet railway engineers were content with tlie ordinary mild steel 
of commerce ; convinced that it would stand any amount of shock in railway bridges. But they did 
not know what it goes through in the works. It was all nonsense to condemn cold worked steels 
simply because they had been cold worked and because there had not been enough shock tests of them. 
He thought himself that 22,000 lb. as a working stress for special steel bars and 25,000 lb. on drawn 
wire would be quite proper practice. Mr. White had refei'red to the advantages of fabric and had 
said that drawn wire was not likely to be used for beams. But he (the speaker) had some years ago 
brought to the Concrete Institute a scheme of a German manufacturer for using drawn wire in beams. 
It was made into a sort of bundle which enabled it to be inserted readily into the reinforced concrete 
beams, and the firm got special advantages from the German Government in the design. Mr. Andrews 
had spoken about the yield point as being the limit from which we should get the working stress and 
the factor of safety ; but it had been pointed out in the paper that in cold worked steels like drawn 
wii'e and twisted bars there was no well-defined yield point. If you stretched steel you created a new 
yield point, and you could stretch it again and create another yield point ; but it was unlikely in 
practice that you were going to get beams continually loaded more and more in a crescendo so as to 
keep on stretching and gettmg fresh yield points throughout the existence of the building. Mr. Pickering 
had referred to the fatigue of metals. Certainly there ought to be a lot more research work, but there 
was great dispute about the fatigue tests that had already been carried out ; papers had been read 
about them, and in all cases it was a great question whether you had purely fatigue or, in large part, 
impact. He (the speaker) thought the effects noticed were largely attributable to mipact ; if you com- 
pared the values in fatigue tests you would find them to be very similar to the effects of impact. Mr. 
Etchells had .talked about the official mind. Experts in logic could be found to demonstrate that 
two and two made two under certain conditions ; but ordinary people said it made four. He (the 
speaker) supposed that the official mind would take the consensus of opinion, and would decide that 
two and two made three-and-a-half. It should be up to the officials to take the best opinion, and to 
judge what was most correct ; not to take a sort of average. Mr. Etchells had also talked about the 
lever arm that it was proposed in the paper should be substituted for the modular ratio ; it was easy to 
calculate the lever arm. Mr. Etchells had also said that perfection would never be reached ; but because 
perfection could not be reached in these tests, that was insufficient reason for taking no notice of them. 
The Chairman added a few further remarks and the meeting terminated. 

168 



E 



CONSTBUCnONAH 



PORTLAND CEMENT. 




PORTLAND CEMENT, 

ITS TESTING AND SPECI- 
FICATION—BRITISH AND 
FOREIGN METHODS. 



By R. E. STRADLING, M.C., B.Sc, A.M.I.C.E., A.M. Am.Soc. C.E. (Lecturer in 
Civil Engineering University of Birmingham). 

I. Essential Properties of a Cement from the Engineer's Standpoint. 
The writer considers that the essential properties which a cement must possess 
to be of use to the engineer are three : — 

(i) Setting time within wotkable hmits. 

{2) Soundness ; i.e. no disintegration with ageing, 

(3) Strength sufficient for reciuirements. 

(i) Setting time.— Wlien a cement is mixed with water the mix gradually 
becomes stifter until ultimately it sets into a hard mass. It is realised that probably 
chemical action is taking place from the moment the water reaches the cement grains, 
and that to develop the full strength of adhesion between two grains they should not 
be interfered with in such a manner as to disturb tliis chemical action. Owing to the 
impossibility of hydrating a large number of grains simultaneously, it is necessary to 
disturb the mass, by miixing, in order to cause the water to reach as much of the cement 
as possible. The chemical action causing " setting " must, then, from practical 
considerations, be interfered with, and the engineer requires to know the limit to 
which it is safe to carry this disturbance. It will be shown later how the chemical 
action can be demonstrated bv measurement of thermal changes, but for the present 
note, it is only necessary to realise that certain arbitrary limits are used, though these 
would appear to have a certain relationship to the chemical changes taking place;. 

It is usual in modern practice to consider that a mixed cement should not be 
disturbed after a point at which a needle i mm. sq. in section just fails to penetrate a 
block 4 cm. thick. This point is known as the Initial set. 

It is suggested that a cement which has an initial set of under one hour should be 
avoided in modern reinforced concrete work. During this hour the cement (in con- 
crete) has' to be mixed, taken to its position, then rammed round reinforcement. Then 
it is further disturbed by the ramming of the next batch of concrete. The term 
" Final " set is also used and is defined in the British Standard Specification in such a 
way as to be equivalent to tlic point at which tlic jienetration of the i mm. needle 
does not exceed 0-5 mm. 

(2) Soundness. — ^Tliis term has a special meaning in connection with Portland 
cement. It ii;is l)ecn found, that after certain cements (used in concrete) have been 
in position in a structure for some time, the mass starts expanding, causing disin- 
tegration. 'I'his action is known as " I'^nsoundncss." 

(3) Strength sufficient for requirements. — By far the greater proportion of 
cement used is utilised for concrete. Ihat is to say its function is to " stick " the 
stone and sand together. Hence the essential " strength " requirement of a cement 
is a high " ceuK'ntitious value." 



D2 



169 



R. E. STRADLING. [CDNCTETE ] 

II. The Specification. 

The specification of a cement then, must so define its nature and properties that 
the preceding three points are assured if a product satisfies the tests laid down. The 
essential requirements of the tests to be enforced appear to the writer to be summarised 
as under : — 

(a) Shall give a real indication of the suitability of the cement for the work in hand. 

(b) Shall be independent, as far as possible, of the personal equation introduced 
by the one performing the tests. 

(c) Shall be capable of indicating the quality of the cement in the shortest time 
possible. 

In general the tests laid down in a specification must also be considered from two 
standpoints : — 

(i) Are they such as can be easily performed in the works ? 

or (2) Are they such as can only readily be performed in a laboratory ? 

It is the intention of the writer in the following pages to indicate the problems he 
considers to be involved in measurements of setting time, soundness and strength, to 
consider the various tests used in Britain, the United States of America, France and 
Germany for the testing of cement, and to show to what degree the various specifi- 
cations really conform to conditions laid down in (a), {b) and (c) above. 

Before, however, anj- detailed tests are examined, it is first necessary to consider 
the general problem of the mixing of a cement with water, i.e. the general problem of 
hydration. 

III. The Hydration and Mixing of Portland Cement. 

The actual amount of water required for the chemical actions of ' ' setting and 
hardening " varies with each sample of cement, but is in the neighbourhood of 9 per 
cent, by weight of the cement used. 

It is not possible to mix a cement with this small amount of water and from two 
to three times the amount is required. 

Within possible working limits the least amount used the better from the strength 
standpoint, providing the setting time is sufficiently delayed to allow of prolonged 
mixing, when small quantities of water are vised. A very convenient method of seeing 
the amount of hydration in a mixed sample of cement is provided by the microscope 
by a similar procedure to that employed in the examination of metals. 

Figs. I and 2 show photo-micrographs of cement clinker from a rotary kiln 
( X 100). The specimen was polished and etched and viewed by vertical illumination. 

Fig. 3 shows a photograph of cement clinker from a stationary kiln ( x 100). 

It will be seen that the structure shown is very definite and quite easily recognised. 
The dark portions are usually termed " Alite " and the whiter matrix " Celite." 

Fig. 4 shows a hardened cement pat (21 per cent, water) which has been polished 
and viewed in a similar way ( x 100), the white portions being unchanged clinker. 

Fig. 5 shows a similar pat but mixed with 23 per cent, water. 

Figs. 6 and 7 show" polished and etched specimens from a pat of mixed cement in 
which the clinker formation is easily seen. Quite large proportions of untouched 
clinker are present, that is to say the whole mass has not been hydrated. With a 
normally ground cement one of the original investigators of this (E. Stern) gives 50 
per cent, as a figure commonly found in neat cements. In cement used in concrete 
this may increase to 70 per cent. (N. C. Johnson). This may explain the fact that if 
old concrete be re-ground to powder, the latter is found to possess some cementitious 
properties. It is considered that finer grinding may help to give a larger hydration 
ratio as the smaller the particles are ground the greater the area exposed to the action 
of water when any given weight of cement is used. It is probable * that the centre of 
cement grain is never reached by water even after many years of exposure in the mass. 

* Desch, Chemistry and Testing of Cement, p. 118. 
170 




PORTLAND C EM EXT. 




Fig. 2. Rotary Kiln Clinker x ioo (v. i). 





.'.i>-."%.^-ty^'''^ 






. >'^;V^> •* # 1 



Fig. 4. Cement Pat (2i"o HyO). 

(Strength 638 lb. at sen'^n days.) 

Polished x ioo (v. i). 






N -'•-W'r^I'*. 



f 4*1 . . 



r*'^' 



:-'^V^^' 



Fig. .s. Ci Misr Pat (23",, HvOV 

(Strength 565 i.n. at seven days.) 

Polished x ioo (v. i). 

Note: Tlio photo-micrographs (Fins, i to 7), for purposes of reproduction, have been reduced 
to two-thirds tlic origiiial size in each diniensioii, so that the amount of magnification expressed in 
diameters is reduced in the same ratio. 

171 



R. E. STRADLING. 



iCQNCKEnEl 





* Fig. 6. Cement Pat. Polished and 
Etched x ioo (v. i). 



Fig. 7. Samh as 6 but .magnified to x 300 ( v. i) 



It seems obvious from this that every means possible should be used to increase 
the proportion hydrated, as the unhydrated areas might more cheaply be filled by sand. 
This hydration is apparently effected by four things at least : — 
(i) Fineness of grinding. 

(2) Manner and amount of mixing. 

(3) Amount of water used. 

(4) Temperature of water used. 

In testing, (i) is already fixed, and does not enter into the problem. The real 
difficulty is to define uniform methods for (2) and (3) . In following through the various 
specifications these problems will be discussed more fully. 

Mixing Rules. 

The Rules laid down by the authorities for the mixing of cement for standard 
tests are as follows : — 

TABLE I. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 

Mixing Rules. 

'British. Mixed by hand with ordinary gauging trowel. 

U.S.A. Mixed by hand. Rubber gloves to be worn and paste kneaded with the hands 

for I minute. Not more than 1000 gms., nor less than 500 gms. to be mixed at 

one time. 
French. Not stated. 
German. Mixed by hand for i minute then placed in Steinbruck-Schmelzer mortar mixer 

for 20 revolutions. 

It will be seen that neither Britain nor France lays down any special notes. U.S.A. 
is rather better, chiefly owing to the addition of specified limits to the amount mixed 
at one time. The lower limit is so high that the small percentages of water usually 
accepted in English practice in cement testing, I do not think could be used. 

The German method would seem to give the best chance of impersonal mixing. 
The type of mortar mill is illustrated in Fig. 8. 

Suggestions have been made in England for designs of mixers (e.g. hyFaiia, Figs. 
9 and 10), but have never been accepted for official specifications. 

Amount of Water (Normal Consistency). 
The various regulations are as follows : — 

* See note on previous page regarding these two figures, 
172 



^ 



CONSTCUCTlC»MAlJ 



POR TLA ND CEMEN T. 




"British. 



U.S.A. 



Elevation. 



Fig. 8. Steixbruck-Schmelzer Mill. 

TABLE II. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 

Quantity of Water. 
[Normal Consistency.) 

(i) Neat Cement — not stated, except that " the mixture shall be plastic when 
filled into the moulds." 

(2) Moytar. — " Sufficient water to wet the whole mass throughout without any- 
excess being present." 

Vicat needle apparatus with plunger i cm. in diam. Neat cement paste used 
— kneaded by hand — tossed 6 times from hand to hand held 6 in. apart and placed 
in rubber ring. Normal consistency when plunger after placing gently on sur- 
face penetrates 10 mm. in J min. For Mortar, water to be used is taken from 
table below : — 



% 


Water for Neat 


% for mix 1-3 


% Water for Neat 


% for mix 1-3 




Cement. 


Ottawa Sand. 


Cement. 


Ottawa Sand. 




15 


9-0 


23 


IO-3 




16 


9-2 


24 


10.5 




17 


9-3 


25 


10.7 




18 


9-5 


26 


IO-8 




19 


9-7 


27 


n-o 




20 


9-8 


28 


II-2 




21 


10 -o 


29 


II-3 




22 


IO-2 


30 


11-5 



French. For neat cement Vicat needle is used with plunger i cm. diam. A pat 4 cm. 
thick is used and consistency is correct when plunger penetrates to within 6 
mm. of the bottom. 

For cement mortar (1-3) for i kilo, of dry material amount of water = 55 gms. 
+ ^P where P = amount required for i kilo, neat cement, i.e., % for mix = 

, % for neat cement 
5-5 + r • 

German. By Boehme's hammer test on a mortar cube. Correct amount of water when 
between the 00th and iioth blow liquid cement just begins to flow out of the 
notches of filling, box. 

As will be seen the British specification is lacking in any precise statement. The 
writer considers this omission may be serious if the personal equation is to be ehminated. 
The Americans and French have practically the same test, but the French limit 
gives a much wetter mix than tlie American, thougli both use more water than is usually 
considered right in F.ngland. 



173 



R. E. ST RA DUNG. 



[CQNCKETEJ 




Fig. 9. Faija's Cement Gauger. 





Fig. ir. Boehme Hammer, Riehle'; 
Pattern. 



Fig. 10. Cement Gauger of Similar Con- 
struction TO Faija's, but made by 
Messrs. Riehle. 




I 



Fig. 12. Boehme Hammer as specified by Germany. 



174 



d 



l^y^Sll^ PORTLAND CEMENT. 



The German test for normal consistency takes advantage of the fact that after 
repeated blows on the mixture of cement, water can be forced up. The Boehme 
Hammer is shown in Figs, ii and 12. 

This test seems to the writer to be quite a sound one. It has been in use some 
years and is still retained. Those who use it regularly appear to approve of it very 
strongly. The only objection the writer has heard passed to this is that the anvil 
block, which is placed on top of the mortar to give a striking surface for the hammer, 
requires very careful placing to prevent jamming against the sides. 

Strength Tests. 
[A .) Tensile Test — Neat Cement. 
The various regulations are as under : — 

TABLE III. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 

Strength Tests. 
A . Tensile Test, Neat Cement. 

'British. Standard briquette, no mechanical ramming or knocking, and only the hands to 

be used ; 24 hours in moist air. 

Then till 7 days old in water ) ^ , 
- Q |- o eacn 

Strength at 7 days at least 450 lbs. = P 

„ „ 28 „ „ „ P +^°° lb. 

U.S.A. None. 

French. Briquette (similar to British), 5 sq. cms. in cross section. 

Strength after 7 days at least 25 kilos, per cm^^ 356 lb. /Q" 
.. 28 „ „ „ 35 „ „ „ ^ 500 Ib./n" 

No difference for sea work or not sea work. 

Strength shall also increase at least 3 kilos /cm - 

(ii 43 lbs. /□" between 7 and 28 days.) 

To be stored in sea water if for sea work. 
German. None. 

{B.) Tensile. Test — Cement and Sand. 
The various regulations are as under :— 

TABLE IV. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 

Strength Tests {contd.). 
B. Tensile Test, Cement and Sand. 
"British. i to 3 by weight. 

Leighton Buzzard sand to pass 20 X 20 and retained on 30 x 30. (Size of wire 

•0164" and -0108" respectively ; mesh. -0336" and -0225".) 

Moist atmosphere for 24 hours. 

In water till 7 days ; at least 200 lb. /Q" = P 

o T, , 10,000 
28 „ „ „ p + ^j_ib. 

Mortar to be placed in mould, heaped up twice and patted down with standard 
spatula. 

U.S.A. I to 3 by weight. Standard Ottawa sand to pass 20 sieve and retained on 30. 
To be considered as remaining on 30 sieve when 5 grms. pass/min. when sifting 
500 gms. Diam. of wires -0165" and -on". 24 hours in moist air and rest in 
water, at 7 days old at least 200 lb. /n" 
.. 28 „ „ ,, ,, 300 Ib./D" 
The average at 28 days must bo more than at 7 days. 

French. i to 3 by weight. Standard Lcucate shore sand supplied by administration. 
Equal quantities of the following materials arc mixed : — 
(i) Cirains pa.ssing 2 mm. (-079") and retained on 1-5 mm. {-o^g") 
(2) Grains passing 1-5 mm. (-059") and retained on i mm. (-039') 

175 



R. E. STRADLING. [CONCRETE ] 

(3) ('.rains passing i mm. (-039") and retained on -5 mm. (-020") 

For sea work and not sea work. 
At 7 days at least 8 kilos/cm^ ^v n^ lb. /n" 
At 28 „ „ „ 15 „ ,. -2i3lb./n' 
- The strength must increase at least 2 kilos /cm ^ (28-6 Ibs/n") between 7 and 28 
days. 
German. None. (For hasty test on constructional work must show 12 kilos /cm* (172 
lb. /D") at 7 days.) 

As will be seen this latter test is used by all four countries, though in Germany it 
is not really a standard test and is only used as a rough works test. 

As a note on these strength tests a consideration of fineness of grinding is now 
required. 

The various specifications are as under : — 

TABLE V. 

SPECIFICATIONS FOR PORTLAND CEMENT. 

Fineness. 

"British (19-20). 

100 grams shaken for j hour on each of the following, in order given : — 

Mesh •00376" 

180 X 180 holes /□" (Wire -0018") 

Mesh -00876" 

76 X 76 ,, ,, (Wire -0044") 

Residue on ist not to exceed i4°o 

,, 2nd ,, ,, ,, 1% 

U.S.A (1917)- • u X „ • • 

50 gms. shaken till not more than '05 gm. passes per minute m the following sieve: — 

mesh -0029 
No. 200, i.e. 200 X 200 holes /□" (wire '0021) 
Residue not to exceed 22%. 

(a variation of 1% allowed and reported as 22%) 
French {191c). 

100 gms. shaken on the following sieves : — 
(i) 324 holes /cm* =2=2080/0" =!^ 41 X 41 

(2) 900 ,, ,, ^ 5800 /D" ^ 76 X 76 

(3) 4900 ,, ,, -- 31500 /n" =2= 178 X 178 

Diam. of wires (i) •2 mm =2= -00788" mesh -356 =2= -014" 

(2) -15 mm :£>: -00592" mesh -1833 mm :^ -0072" 

(3) -05 mm =£i: -00197" mesh -0929 mm —•00365" 
(a) For sea work. Residue on 90c not to exceed 10 % 

{b) Not for sea zvork. ,, ,,4900 ,, ,, ,, 30% 

,, 900 ,, ,, ,, 10% 

German (1909-1920). 

100 gms. shaken — no time given. Sieve 900 holes /cm* =21 76 X 76. 
Mesh = -222 mm. =2= -00875" (limits = •215--240 mm.). 
Residue not to exceed 5%. 

The effect of fineness of grinding on the strength as given by the two strength 
tests {A) and (B) is shown in Table VL : — • 

TABLE VL 

FINENESS. 
Professor R. K. Meade. 

Showing increase in sand strength due to fine grinding. 
Tensile strength in pounds per sq. inch. 

NEAT. 

I day. 7 days. 28 days. 3 ninths. 6 ninths, i year. 2 years. 

As received . . . . 327 630 725 720 760 825 850 

Ground to pass a 200 mesh « 

sieve . . . .210 525 540 540 560 575 560 

176 



1 



C0N5TRUCT10NA 
EMGH^EERING 



iALl 



PORTLAND CEMENT. 



I 
I dav 



As received 
Ground to 
sieve 



pass 



a 200 mesh 



3 MORTAR. 
7 days. 28 days. 
^78 357 



3mntl)s. 6mnths. 
387 390 



— 480 



575 



615 



I year. 2 years. 
410 425 

623 640 



It would seem to be extremely doubtful if the test of neat cement is really valuable 
as a measure of the quality of a cement. As is shown in Table VI. the finer a cement is 
ground the lower the strength given by this test, but the higher the value given by 
cement and sand test. 

If this is the case there does not appear to be much reason for specifying this test. 

The writer considers the cement and sand test the most important of the strength 
tests in use. It obviously is some measure of the power the cement possesses of 
sticking together particles of stone — which property is the one most desired in a cement. 

No special machine is specified for the actual breaking of the briquettes. The 
rate of loading is specified and in the British specification the shape of the grips of the 
machine also. The grips should be greased. 




Fig. 13. Professor Coker's Diagrams of Stress. Distribvtion in Celluloid Models of Cement Briquettes. 

It may be interesting to consider an experiment of Prof. L. G. Coker, F.R.S., on 
the influence of the form of briquette on the stresses produced. 

By making models of the briquette in celluloid or some like transparent substance 
and examining by polarised light when under load, it is possible (by methods brought 
to a high state of perfection by Prof. Coker) to obtain a measuie of the stress distri- 
bution present. 

This distribution is shown in Fig. 13.* 

It will be seen that tlio maximum stress is something of the order of 1-75 x mean 
stress. 

He experimented witli the various forms used in the different specifications and 
found a variation in this constant from 1-7 to 1-95. 

Thus altiiough tiic absolute \ahic of these constants may not be applicable to such 
a material as cement since tlicv were determined for celluloid, etc., still it is reasonable 
to suppose that they indicate tiie order of magnitude of the stresses and that they 
certainly sliow that tiie strengths of varying shajios of briquettes cannot be compared 
with each other directly. 

( I'o he I oil eluded.) 



I'lciin Eniiinecring, 1912, p. 825. 



177 



A. E. WYNN. 



l^SClCTE] 




THE AMERICAN 
"FLAT SLAB" 
TYPE OF 
BUILDING: ITS 
ADVANTAGES 
AND DESIGN. 



By A. E. WYNN, B.Sc, Assoc. M.Am. Sec. C.E. 
{Continued from j}agc 102 of our February issue.) 

Distribution of Steel to resist Moments. — To resist the negative moment over the 
support in each strip A take the sum of the areas of steel in one cross band and one 
diagonal band. To resist the positive moment in each strip A take area of steel in 
one cross band. To resist .the negative moment in strip B take the steel included 
in width of strip B. To resist the positive moment in strip B take area of steel in 
one diagonal band. 

Compression in concrete as before. 

Example : — 

Interior panel 20 ft. X20 ft. L=20 ft. 

Loads and stresses as before. Thickness of slab, sizes of cap and depressed panel 
will be same as in previous example. 

128,000X20 .^ ,, 

Strip .-i. +M=IFL/8o= — =32,000 ft.-lb. 



Effective depth 8 J 
Area of steel in band = 



80 
ni 



7t in- 

32,000 X12 



Strip B. +i\/=IFL/i20 = 



16,000 X -874X7-25 
128,000X20 



=3"79 sq. in., say 19^ in. ro. bars. 



=21,340 ft.-lb. 



Effective depth 8^-1^=7 m. 

21,340X12 
Area of steel ~ 



2-62 sq. in., say 14 J in. ro. bars. 



Strip A. 



16,000 X -874X7 
-M^WL/120. 

Area of steel=2-53, say 13 J in. ro. bars. 
-Depth of depressed panel is found as before=i2 in. 

128,000X20 „ ,, „ 

-M=l^L/30= -^^ =85,400 ft.-lb. 



30 

Effective depth 12— i|=ioJ 
85,400X12 



Area of steel- 



:7-2i sq. in. say 37 J in. ro. bars. 



16,000 X -868 X 10-25 

It is common practice to carry all the bars over two bays, in order to save steel 
and splicing them so that half the bars are spUced over each column. The bars in 
the rectangular bands are carried to the quarter point, or in this case 5 ft. beyond the 
column, and the bars in the diagonal bands are lapped 2 ft. or sufficient to develop 
bond. 

178 



D.P. = ^^ ^\^ Q^o^^^ — 2—7'^^' ^^y ^ ^^- This depth would require 40 \ ro. 



k-gSofNli^NG^ AMERICAN "FLAT SLAB" TYPE OF BUILDING. 

If we adopt this method the steel to resist the negative moment in strip A will 
be one diagonal band or fourteen bars plus one rectangular band or nineteen bars 
plus one half a rectangular band from the bars that extend to the quarter point, or 
nine bars, making in all forty-two bars, which is more than sufficient, as we have 
found we require thirty-seven bars. In this method all of the bars are bent up into 
the top of the slab at the column. 

If we carry all the bars only over one panel then we should have fourteen bars 
from the diagonal band, leaving twenty-three to be provided from the rectangular 
band, and we should bend up twelve bars from each side of the column, carrying 
them to the quarter point and leaving seven bars straight in the bottom of the slab. 
The widths of the bands will be •4L or 8 ft. 

Comparing the two designs we see that the first requires 3-7 lb. of steel, and the 
second 3-45 lb. of .steel per sq. ft. 

In the above examples we have taken the width of the depressed panel as L/3 
or 6 ft. 8 in. This is the minimum width allowable ; however we could have made 
it greater if desired. Instead of assuming the width and finding the necessarv depth, 
we could have assumed a depth and found the corresponding width to give the required 
amount of compression. 

Supposing in the last example we had wished to use a drop of 3 in., giving a total 
depth t'=^ii\ in. and effective depth of 11 J— if =9^ in. Then required width of 
85.400 

350 X -396 X -868 X 9-5' 
bars for negative moment. 

It is usual in four- way design to bend up all the bars over the columns and, accord- 
ing to the amount of steel thus available, to proportion the size of the depressed panel. 

It is not advisable to make the drop less than 2 in. 

We will now consider the design of a slab without a depressed panel. The 
following two rules are taken from the Chicago Building Code. 

(i) The sum total of the positive and negative bending moments, regardless of 
sign, shall be equal to that computed by the formula : — 

B.M. = W^L/8(i'53 — 4^+4-18^^), where "k" is the ratio of radius of the column 
cap to L. 

(2) This B.M. is to be divided between positive and negative moments in same 
proportion as in typical square panels for two-way or four-way systems as given above 
for interior and wall panels respectively. Compression in the concrete : Width of 
beams shall be width of steel bands, and where not sufficient use compression steel 
in the bottom of the slab. 

Example : — 

Panel 20 ft. X20 ft. L = 2o. Two-way design. 
Live load^2oo lb. per sq. ft. 
Finish =20 

Assume a 10 in. slab =120 lb. 
Z£;=i2o +200 +20=340. 
1^=340X400 = 136,000 lb. 

, 4-5/2 
^= — ^—=-1125. 
20 -^ 

Total B.M. = i36,oooX2o/8(i-53 -4^+4-18^3). 

=340,000(1-53 —4 X-ii25-l-4-i8x-i 1253). 
=365,000 ft. lb. = irL/7-45. 
In the previous example the total B.M. was irL/{i/30-|-i/6o + i/i20 + i/i2o)2 

= WL/t5- 

179 



A. E. WYNN. [CQNCRETEi 

—M in A band = -5 of total moment. 
+M „ „ „ ^-15 
-M „ B ,, =--125 
+M „ „ „ =-i25 ,. 
Dividing the new moment in the same proportion we get — 

—M in band A= -5X365,000 = 182,500 ft.-lb. for two bands. 
+M ,, „ ,, = -25x365.000=91,250 
-M ,, ,, 5=-i25X 365.000=45,625 ,, ,,. ,, 

-\-M ,, ,, ,,=-125X365.000=45,625 
Either shear around the cap or compression at the column will govern the thick- 
ness of the slab. 

c, 136 ,000 -3-i4(4-5V4) X3 40 e ,, 

Shear= ^ =04 lb. per sq. m. 

3-14X4-5X12x875 -I- K H 

182,500/2X12 

which is less than the allowable compression at thecohimn= — ^=144,000. 

-068 X8-75 

144,000 

Stress in the concrete= — - — X2=693 lb. sq. in., 

I2XIOX-396X8-75 "^-^ ^ 

so that the assumed thickness of slab was correct. The amount of reinforcing is 
found as before. 

By using some of the straight steel in the bottom of the A bands as compression 
steel over the column, it would be possible to cut down the thickness of the slab 
shghtly, or special compression steel can be used, but it would not be economical in 
most cases. 

The next point to consider is the design of a rectangular panel. 

Where the length does not exceed the width by more than 5 per cent, the design 
is the same as for a square panel, taking L as the mean of the two sides. When the 
length exceeds the breadth by more than 5 per cent, the following rules are to be 
observed. 

Four-Way System : — 

(i) Amount of steel in strip A long direction, both positive and negative, shall 
be same as required for same strip in square panel whose side equals long side of rect- 
angular panel. 

(2) Amount of steel in strip A short direction, both positive and negative, same as 
for square panel whose side equals the short side of the rectangle. 

(3) Amount of steel in strip B, positive and negative, shall be same as required 
for similar strip in square panel of side equal to the mean of short and long sides of the 
rectangle. 

(4) Steel in the short side should not be less than two-thirds the steel in the long 
side. The long side should not exceed the short side by more than one-third. 

Two-Way System : — 

(i) Amount of steel for both positive and negative moments in strip A shall be 
determined in the same manner as for the four-way above. 

(2) Amount of steel in strip B, both positive and negative, running in short 
direction, shall be equal to that required for same strip in square panel whose side 
equals long side of the rectangle. 

(3) Amount of steel in strip B, both positive and negative, running in long direc- 
tion, shall be equal to that required for same strip in square panel whose side equals 
short side of the rectangle. 

(4) Steel in strip B long direction should be not less than two-thirds that in the 
short direction. The long side should not exceed the short side by more than one- 
third. 

180 



i 



CONSTKUCnONALJ 
EMOrNElERlNG ^-J 



AMERICAN "FLAT SLAB" TYPE OF BUILDIXG. 



If these rules are followed there will be no difficulty in designing rectangular 
panels. 

Roof slabs are designed in exactly the same way as floor slabs, only the live load 
is very small, and deflection rather than strength controls the design. It is customary 
not to make the slab thickness less than 6 in., though for small panels, say 15 or 16 ft. 
square, 5 in. will be found satisfactory. 




TVVO-W.W SviTLM OF FORMWORK. 

Note inadeup Deck Panels in foregrountl. 




The Two-Way System of Formwork. 



If the roof is designed for the actual live aiul dead loads loo small a percentage oi 
steel will be obtained to resist the stresses due to temperature changes and the slab 
may crack. It is therefore usual practice not to design a roof slab for less tlian 90 lb. 
per sq. ft. ; this can be taken to include tlie snow load, roof finish and fill if any. Tlic 
slab itself can be pitclied to the necessary slope to avoid using cinder fdl. 

All tlie above rules for design apply only to a building that is at least three bays 

181 



A. E. WYNN. 



[CQNCBETEJ 



wide and that is of frame construction, that is the slabs are poured monolithic with 
the columns. 

Buildings are designed that are only two bays wide, usually 25 or 30 ft. bays, 
but they are unusual, not economical and require special treatment, so they will not 
be discussed here. 

As it is necessary that the wall columns be capable of taking some tension it is 
not recommended that flat slab floors be used in conjunction with exterior bearing 
walls, either old or new. If, however, it is necessary to use an exterior bearing wall 
the following rule from the Chicago Building Code should be followed : — Lay up in 
cement mortar and stiffen with pilasters as follows: for 16 in. walls 4 in. pilasters, for 
12 in. walls 8 in. pilasters. Width of pilaster to be not less than the diameter of the 



Sof^c/ a/ 




r/G.6 






F/G 7 



no a 



^/<S 9 



column nor less than one-eighth the distance between pilasters. They are to be 
located as far as possible opposite to the columns and be corbelled out 4 in. at the 
top, starting at a level of base of cap. 

Not less than 8 in. bearing is to be provided the full length of the wall. Co- 
efficients of bending moment are to be the same as for interior panels, but increase the 
positive moments in strips A and B 50 per cent, between wall and first line of columns. 

Having dealt with all the points in the design of the slabs themselves, it is now 
necessary to consider the design of the columns, wall beams, and the provision for 
carrying concentrated loads. 

The interior columns are not usually designed for eccentric loading, but their 
diameter should not be less than one-twelfth the clear height nor less than one-twelfth 
the panel length ; this rule will cover all ordinary cases of eccentric loading. 

182 



f»,OTr^yreucTioNALJ AMERICAN "FLAT SLAB" TYPE OF BUILDING. 



.E7'<GrNE£BING — i 



Wall columns are constructed with brackets and depressed panels (see Fig. 6). 
The depressed panels are similar to those in the interior bays only they are half the 
width . 

The brackets are usually made the full width of the columns and the depth is 







ym^^ 






New Building for Haynes Automobile Company, Kokomo, In'd. — Typical FolT^-Wav System. 
Nots Spouting System. 




governed by the allowable shear on the depth of the bracket and on the slab along 
the perimeter of the bracket. It is good practice to reinforce the bracket to obtain a 
good bond to the column, tying the bars back to the column steel ; a proportion of 
the vertical shear can be taken by these bars. 

E 183 



A. E. WYNN. 



[CONCBETEJ 



The wall columns have to resist a bending moment as Avell as the vertical load, 
and are therefore designed for bending and direct compression. 

It is usual to assume a B.M. of WL/Go at the floors and IVL/^o at the roof. The 





^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^S^ j 


■ "i^^i 


'^SinB^"' < ^^^E^^Biy^^^BK^' 


^m^mg w 


MKMlJ. I^HBL^^r^EE^Sii 



Department Store — Orn'amestal Column Cap and Depressed Panel. 




Interior View of Warehousi; — N'o Diprkssed Panel. 



columns both above and below the slab are designed for this moment. Short bars 
are used, bent so that they are on the tension face of the column both above and 
below the slab (see Fig. 6). They should extend to a point one-third the distance 
from the floor line to the base of the cap and the amount of steel required for the 



r&g;?.ml^NG^ AMERICAN "FLAT SLAB" TYPE OF BUILDING. 

above moments should be independent of that required to carry the vertical load. 
At the roof they are bent over into the slab. 

Wall beams are designed in three principal ways : (i) a deep narrow beam ; (2) 
a shallow wide beam the depth of the depressed panel, this allows for better lighting 
and is the best method ; (3) when still more Hght is required the wall beams are 
placed above the slab (see Figs.. 7, 8, 9). 

There is always a half band of steel adjacent to the wall beams, and as this has 
a smaller effective depth than the steel in the beam, part of it cannot be fully stressed 
until the steel in the beam is overstressed, consequently the beam must be designed 
to carry some proportion of the slab load. The beams are also under torsional stress 
due to the deflection of the slab and therefore should not be made too narrow. 

There are various opinions as to what proportion of the slab load should be borne 
by the wall beams. It varies, according to different regulations, from one-fifth to 
one-twelfth of a panel load uniformly distributed along the beam. 

The Chicago Code specifies one-fifth of a panel load to be carried by the wall 
beams, but this seems to be excessive. Probably one-eighth is the best value to use, 
although the writer uses one-twelfth with successful results. In addition, of course, 
there is the dead load of the beam and wall to be allowed for. 

All corner beams should be designed for one-quarter of a panel load as they 
receive a greater proportion of the slab load. 

The wide shallow beam, the same depth as the depressed panel, is best suited to 
resist the torsional stresses and gives the maximum stiffness to the structure. 

Where the beam is carried above the slab it is important to use plenty of stirrups 
to tie the slab to the beam, also as there is a possibility of cracking between the slab 
and the beam it is well to provide sufficient reinforcing in the bottom of the beam above 
the slab to carry the dead load of beam and wall. 

All outside surfaces of wall beams should be reinforced to resist temperature 
stresses. 

When the beam is carried up to the window sill the whole depth may be utilised, 
although it is good practice not to use less than four bars in the beam. 

Concentrated loads on the slab are best carried by beams which are always used 
to frame around stairs, elevator openings and to carry heavy walls (see Fig. ia). 

Whenever possible the stairs and elevator shaft are placed in one panel, preferably 
in the corner of the building or outside the building altogether. This avoids cutting 
up the slab with beams and gives a clear working space. 

In addition to the concentrated loads all beams occurring on the -centre line of 
the columns should be designed to carry one-quarter of a panel load uniformly dis- 
tributed. These interior beams may be made wide and shallow, the depth of the 
depressed panel, or narrow and deep. 

When the four-way system is used it is advisable to put a few bars in the bottom 
of the slab diagonally across the corner panel to tie in the beams. If the concentrated 
loads are light, such as tile partitions, they may be safely carried on the slab itself as 
tlie load is distributed over a considerable width. 

Tests on flat slab buildings have been very numerous and they all show that 
the ordinary method of design is conservative. Deflection rather than stress controls 
the design of flat slabs and slabs designed by the Chicago Code should not deflect 
more than 1/800 of the span, tests show that most of them do not deflect much 
more than half this under a load equal to twice the load for whicli the slab is 
designed. 

The writer's firm recently tested a floor slab designed by a nuu h less conservative 
method than called for by the Chicago Code and the deflection at the centre of the 
slab, under a live load of I 3 times the designed load, was 1/1300 of the span. 

'ilic stress in Ihe steel obtained from exlensonieter readings are always very 



A. E. WYNN. [CONCKETE] 

much less than the calculated stress. When tested to destruction the slab yields very 
slowly, showing that danger of collapse from sudden overloading is very remote. 

A few practical points in the construction of flat slab buildings will now be 
mentioned. 

As in any type of reinforced concrete structure it is important that the steel bars 
be held rigidly in position to prevent displacement. This is done by using spacer bars 
of various makes ; these are slotted to receive the bars according to their spacing, using 
about three bars to a band. Spacer bars are not necessary if the bars are carefully 
wired together at their intersections, but they facilitate placing and ensure correct 
spacing. The top steel. is supported by either concrete blocks about 6 in. square or 
by special steel chairs made for the purpose, about three on each side of the depressed 
panel being required. 

Columns should be poured up to the bottom of the cap or bracket and allowed 
to settle about 12 hours before pouring the slab, otherwise there may occur a crack 
at this point. 

Construction Joints should be vertical and through the centre of the bay midway 
between columns. 

Formwork for fiat slab buildings is very simple. The interior columns and caps 
are usually round and steel forms are always used. The wall columns are rectangular 
and it is economical to keep the same section throughout as far as possible. 

One floor of slab forms is used for buildings up to six storeys, above that height 
two sets will be more economical. 

There are two general methods of building flat slab forms. The first may be 
called the one way method. In this the deck consists of " one by sixes " cleated 
together to form panels of convenient size to handle. The deck is carried on " three 
by six " joists about 14 ft. long and about 30 in. on centre. The joists are carried on 
" four by four " posts about 7 ft. apart and resting on wedges to faciUtate stripping 
(see illustration at top of this article.) 

In the second or two way method the deck is made as before and is carried on 
" two by sixes " spaced 24 to 30 in. on centre. These in turn are carried by " four 
by six " girts about 5 ft. on centre. The girts are carried on " four by four " posts 
about 5 ft. on centre. 

Of course the lumber sizes and spacing depend on the thickness of slab to be 
carried. 

After stripping about four posts to a panel are left in, these usually bear directly 
on a loose board in the deck so that the stripping can take place without disturbing them. 

MEMORANDUM. 

Concrete Mattress Blocks. — The following particulars are abstracted from an article 
in the Engineering News- Record : — 

Flexible concrete mattress construction by stringing pre-cast concrete blocks on 
steel cable, as beads are strung on a thread, is the method adopted in improving the 
channel of the Miami River at Dayton, Ohio. The area of mattress formed by 500 
blocks is 1,000 sq. ft., each block being 24 by 12 by 5 in. and weighing about 118 lb. 

The blocks were moulded and stored in a central yard. Block distribution by 
wagons, with a special body, was found to be most economical owing to the scattered 
locations of the placing operations, the steep descents from the levee tops to the beach 
and the rough and soft roads. The blocks are distributed along the work in the num- 
bers required, so as to keep short the distance they must be carried in placing ; in 
• practice this distance averages perhaps 20 ft. 

Wire rope on reels is hauled to a point on the levee top, central to the operation in 
progress. The rope, after being straightened, is cut into lengths twice the width of the 
mattress and enough longer to provide a loop for anchorage to the toe wall and " pig 
tails " at the free ends for anchorage to the edging blocks. The cut ends of the rope 
are threaded through holes in the blocks. 

186 



RESEARCH. 





RESEARCH. 

SERVICE TESTS ON 

CONCRETE FLOOR 

TREATMENTS. 



Bureau of Standards, Washington. 



Some interesting teats were recently undertaken by the Bureau of Standards, 
Washington, D.C., on concrete floor treatments, and we jtublish below a short 
abstract from the Report on these tests. In describing the tests, it is stated in the 
report that the materials iised were applied to slabs in the corridors of the Bureau of 
Standards Building, where some of the floors began to dust and crumble. We would 
here remark that a concrete floor properly made, and with the right aggregates should 
not need any treatment for dusting. But apart from this, the experiments made 
are useful in shounng what has proved successful in overcoming the trouble, should 
it arise. — Ed. 

PURPOSE OF TESTS. 

Numerous inquiries for information concerning the relative merits of various concrete 
floor treatments have led to a comparative study of several proprietary treatments 
and a few " home treatments." The investigation has been based mainly upon 
observations of treated concrete floor panels under actual service conditions, and, 
therefore, the results are not quantitative or necessarily conclusive, but are in general 
indicative of what may be expected of the various treatments when exposed to such 
conditions for the stated periods of use. Pending the development of a suitable 
apparatus for making quantitative wear tests, it is believed that the knowledge gained 
from this study will be of considerable value since it shows the behaviour of the 
treatments placed side by side under as nearly the same traffic conditions as could be 
obtained for a test of this kind. 

description of tests. 

The materials were applied to the slabs in the corridors of the North-west Building 
of the Bureau of Standards, which is used for laboratory purposes and was completed 
in March, 1918. The building was occupied shortly after this time and very soon the 
floors began to dust and crumble at the surface. Hence, it may be said that these 
floors offered an excellent opportunity for determining the merits of such treatments. 
The first materials were applied about five months after the floors were completed 
and other treatments were applied during the following six months. 

The sections of tlie floor which are referred to as panels are eight feet square, i.e., 
they extend the width of the corridor and eight feet along its length. The traftic on 
the different panels is similar, but since the entrance is at the centre, it is evident 
that the panels near the entrance are subjected to more use than those near the ends. 
With the exception of the fact that laboratory machines and office fixtures are 
occasionally moved over the floors, the panels are subjected only to light foot traffic. 

The effect of the traffic was studied in comparison with panels which were left 
untreated. The determination of the wear is based on careful observations. The 
relative hardness was measured roughly by the resistance of the surface to scratching 
with a steel-pointed tool. 

MATERI.\LS. 

The materials included in these tests comprised seventeen proprietary materials, 
which were in most cases submitted by the manufacturers, and the home treatments 
were prepared in the laboratory according to formulae which have been recommended. 
These latter were : — Sodium Silicate ; Aluminium Sulphate ; Linseed Oil ; Fuel Oil 
and Soap ; and Soap Treatment. 

187 



RESEARCH. [(JJNCSETE 



In order to avoid difficulties arising from the direct reference by trade names tlie 
materials and tests are described under reference letters. 

RESULTS OF TESTS. 

Treatments A to D consisted of a solution of magnesium fluosilicate of varying 
strengths between 87 per cent, up to 15 per cent., and gave varying results, some of 
which were satisfactory, according to the strength of the solution employed and the 
method in which it was applied. 

Treatments E and F. — Here again magnesium fluosilicate was used, but with an 
admixture of zinc fluosilicate in one instance and magnesium sulphate and free hydro- 
fluosilic acid in the second case. The results were not satisfactory. 

Treatment G. — This was a 16 per cent, solution of zinc sulphate with about 4'3 per 
cent, free sulphuric acid. It was applied without dilution in two coats. After the 
first treatment had dried for four hours, the surface was scrubbed with hot water and 
mopped dry, when the second was applied. 

This panel has been in service two years and three months. The surface is very 
hard and uniform. No signs of wear are apparent. The treatment gives a darker 
appearance than the original concrete. 

Treatments H and I consisted of solutions of sodium silicate, with, in one case, 
small addition of organic acid. 

After two years and two months the surface was in both instances hard and 
uniform, showing no signs of wear. 

Treatment J. — A 15 per cent, solution of aluminium sulphate applied in three 
coats which were dilutions of the original solution as follows : ist, one part solution 
to two parts water ; 2nd, one part water to one part solution ; 3rd, two parts solution 
to one part water. The treatment was applied liberally with a whitewash brush at 
intervals of 24 hours. 

This treatment was applied to several panels in the corridor and to the floor of 
one large laboratory room, where it was necessary to keep the dust down on account 
of the machinery. The treatment has been in use one year and six months and has 
proved quite satisfactory. The surface is not quite so hard as was obtained by some 
of the other treatments, but it has been effective in holding the dust. This is a very 
economical home treatment which can be easily applied without interfering with 
the traffic. 

Treatments K and L. — The first of these was a grey paint consisting of a pigment 
of basic lead sulphate, sihceous matter and carbon in a tung oil rosin varnish vehicle 
(mineral spirits thinner), and the second was a china wood oil varnish. Neither of 
these treatments can be said to be very satisfactory. In the case of Treatment M, 
however, where china wood oil varnish was also used, the surface to which it was 
applied showed no appreciable signs of wear after two years and two months. 

Treatment N. — The material consisted of a thin-bodied mineral spirits varnish 
applied in two coats at an interval of 24 hours and kept covered with a bridge of plank 
until dry. 

The panel has been in service two years and one month. The coating seems to be 
worn through where most used, as shown by the lighter colour at these places. This 
panel was originally weak and crumbling badly, and hence the test was quite severe. 

Treatment 0. — This was a grey paint with a pigment of basic lead sulphate, zinc 
oxide, barium sulphate, siliceous matter, and carbon in a linseed oil, rosin (and pro- 
bably some tung oil) vehicle, having a mineral spirits thinner. 

This panel has been in service one year and five months, and shows no signs of 
wear except a few scratches which were probably caused by moving machinery over it. 
The treatment gives a wax-like surface, which is not especially resistant to scratching 
but seems to be reasonably durable under foot traffic. 

Treatment P. — This was a very thick paint consisting of a pigment of zinc oxide, 
lithophone and bone black in a varnish vehicle containing rosin. It was applied in 
one coat after the floor had been thoroughly swept. 

This treatment has been in service one year and six months. It shows several 
large scratches due to moving machinery over it and a few small spots have blistered 
and worn away. The thick film obtained with this material is very pleasing to walk 

188 



upon but has not proved durable under the conditions to which it has been subjected. 
It is beheved that a preUminary roughening of the concrete would avoid blistering 
and give a coat that would be satisfactory for ofhce purposes. 

Treatment Q. — This treatment consisted of a solution of heavy hydro-carbon wax 
in a light hydro-carbon oil applied to the surface in two coats 24 hours apart. 

The panel has been in service two years and three months and shows considerable 
wear. The object of this treatment is only to hold the dust, and no claims are made 
as to hardening the surface. 

Treatment R. — This consisted of a mixture of waxes applied to the floor in a 
molten condition. The object of this treatment is similar to that of Material Q. 
More wax is left on the surface, which acts as a binder to loose particles. One panel 
and one office room were treated with this material. Both show considerable wear. 
This has been in service two years and four months. 

Treatment S. — This treatment consisted mainly of linseed oil with a small addition 
of citronella. It was applied in one coat and kept covered until dry. 

While this panel has not proved entirely satisfactory, it appears to be harder at 
this time than it was one year ago. The panel probably should have had two applica- 
tions instead of one. The directions advised one coat for new floors and two coats 
for old, badly worn floors. The appearance obtained was not uniform, which indi- 
cates that the proper amount of the treatment was not applied, and hence it is believed 
that little weight should be given the test. 

Treatment T. — This consisted of four applications of raw linseed oil thinned with 
turpentine. 

It has been in service two years and two months. The results obtained at first 
were not satisfactory but the surface appeared to harden gradually until at present it 
is quite hard. It appears to be resisting the wear very well. 

Treatment U. — This treatment and the one following are what might be called 
janitor processes. It has been noticed that concrete floors under actual use some- 
times take on a polish or present a wax-like appearance. In order to determine if this 
condition was due to the precipitation of soap in the concrete, some sections of the 
floor were frequently scrubbed with a thick soap solution. The polished condition did 
not occur in this case, which was believed to be due to the fact that the floor was very 
porous and hence the solid matter from the treatment was not retained in the concrete. 

Treatment V. — This was an emulsion of fuel oil and soap in the proportion of three 
quarts of oil, two bars of ivory soap and four gallons of water. This treatment was 
not included in the series described above, but was applied recently in the corridors of 
another building, the floors of which were originally much better than those described. 
The emulsion was applied with a mop at intervals of a week or two. About ten 
applications were made and the floors were greatly improved. They do not appear 
to be dusting and the surface is somewhat harder than the original. This application 
leaves the floor slippery for a few hours. 

CONCLUSIONS. 

1. The above-described experience with materials of the magnesium fluosilicate 
class indicates that very good results may be obtained by such treatments, but that 
there is a need for more knowledge concerning the proper strength of solution and 
method of application. 

2. Tlie zinc sulphate treatment has given excellent results. 

3. Tlie surface coating materials are most effective in entirely eliminating the 
dust. The length of service tliat can be obtained from this type will usually be 
limited to a year or two, depending on the nature of the traffic, but since the greater 
portion of the floor does not usually receive a large amount of wear, the worn places 
may be resurfaced at a small expense. 

4. Two home treatments, viz., I and J, have proven very successful and are quite 
inexpensive to apply. The following instructions are given for the use of the home 
treatments : — 

A. Sodium Silicate Treatment. 
Coiumrrcial sodium silicate usually varies in strength from 30 to 40 per cent. 
sohition. It is ([uite viscous and lias to be thiinuHl with water before it will penetrate 

189 



RESEARCH. ICQNCBETEJ 

the floor. In ordinary cases it will be found satisfactory to dilute each gallon of the 
silicate with four gallons of water. The resulting five gallons may be expected to 
cover 1,000 sq. ft. of floor surface, one coat. However, the porosity of floors varies 
greatly,' and the above statement is given as an approximate value for estimating 
purposes. 

The floor surface should be prepared for the treatment by cleaning free from 
grease, spots, plaster, etc., and then thoroughly scrubbed with clear water. To get 
the best penetration the floor should be thoroughly dry, especially before the first 
application, and, if practical, it is well to let it dry for several days after the first 
scrubbing. The solution should be made up immediately before using. It may be 
applied with a mop or hair broom and should be continuously brushed over the surface 
for several minutes to obtain an even penetration. An interval of 24 hours should be 
allowed for the treatment to harden, after which the surface is scrubbed with clear 
water and allowed to dry for the second application. Three applications made in this 
manner will usually suffice, but if the floor does not appear to be saturated by the 
third application, a fourth should be applied. 

This treatment when properly applied gives a very hard surface that is bright 
and uniform in appearance. The commercial sodium silicate can be obtained from 
wholesale druggists at a cost of 40 c. or less per gallon. 

B. Aluminum Sulphate Treatment. 

The solution of aluminium sulphate for this treatment should be made in a wooden 
barrel or stoneware vessel. The amount required may be estimated on the basis of 
one gallon of solution for each 100 sq. ft. of area. For each gallon of water 2-| lb. 
of the powdered sulphate will be required. The water should be acidulated with 
commercial sulphuric acid by adding 2 c.c. of the acid for each gallon. The sulphate 
does not dissolve readily and has to be stirred occasionally for a period of a few days, 
until the solution is complete. 

The floor should be cleaned of grease spots, plaster, etc., then thoroughly scrubbed. 
When the surface is entirely dry, a portion of the sulphate solution may be diluted 
with twice its volume of water and applied with a mop or hair broom. After 24 hours 
dilute a portion of the original solution with an equal volume of water and apply in 
the same manner as the first. Allow another interval of 24 hours and make an appli- 
cation, using two parts of the sulphate solution to one part of water. Each applica- 
tion should be continually brushed over the surface for several minutes to secure a 
uniform penetration. After the third application has dried, the surface should be 
scrubbed with hot water. 

This treatment will give good results at a cost about equal to that of the sodium 
silicate treatment. 



MEMORANDA, 

Water Gauge for Concrete. — In view of the importance of accurately gauging the 
water content in batches of concrete, a device which is shortly to be put on the market 
by the Austin Machinery Corporation, of Chicago, will be of considerable interest to 
engineers in this country. This device, the total weight of which is about 200 lb., 
takes the form of a water meter specially adapted for use with concrete mixers. The 
pump is operated from the shaft of the mixer, and the meter operates automatically. 
By setting a pin on the meter any pre-determined amount of water is supplied to each 
batch of concrete, the supply being controlled by a two-way which is actuated by the 
starting lever of the mixer. It is stated that the device has been extensively tested, 
with satisfactory results. 

Shearing Stresses in Rectangular Reinforced Concrete Beams.— In the concluding 
part of this article which appeared in our February number, page 85, the followmg 
correction should be made: sixth line Irom the bottom of the page; after X^X, the 
last par ol the senten( e should read : 

ac itself having the inclination with the horizon. 

190 



T 1r CONSTRUCnCMA 



1 



CONCRETE IN THEORY AND PRACTICE 



CONCRETE IN THEORY 
AND PRACTICE. 

A practical section especially written for the assistance of sttidents 
and engineers, and others who are taking up the study of reinforced con- 
crete, or who are interested in the subject on its educative side. 

REINFO'RCED CONCRETE SIMPLY EXPLAINED. 

By OSCAR FABER, O.B.E., D.Sc, etc. 

In this series of articles it is proposed to keep explanations so simple as to be 
intelligible to anyone desiring to understand the underlying principles of reinforced 
concrete without wading through a lot of mathematics. The results will be accurate 
and will agree with L.C.C. regulations, but will be more easy to understand. The 
articles should also form an excellent introduction to those who will need to follow 
them up with a more advanced work. — Ed. 



CHAPTER \.— continued. 
Design of Columns. 

70. The calculation for the column in 
Section 69 was lor a top tier column, that 
is, one which stopped at the beam it 
supported. 

Such a column is subjected to greater 
bending stresses than a column of a lower 
tier which runs up above the beam it 
carries, because in that case the bending 
moment from the beam is carried partly 
by the upper length of column and partly 
by the lower. 

Suppose, as an example, we now cal- 
•culate the stresses in a standard outside 
column 16 in. x 16 in., supporting a 
standard T beam 20 in. x 8 in. 25 ft. 
span, carrying 25,000 lb. distributed 
load at roof level, and also supporting 
a similar beam and load at third floor 
12 ft. 6 in. lower, a second floor beam 
12 ft. 6 in. lower still, and so on. Now 
the stresses in the upper tier are exactly 
as calculated in Section 69. Those 
in the lower tier under third floor will 
now be calculated. 

Column carries 12,500 from roof level. 
,, ,, 12,500 ,, floor level. 

25,000 total. 
Equivalent area of standard 16 in. 
X 16 in. column = 300 sq. in. 

25,000 



300 



Therefore direct stress == 
53 lb./in.2 

Now, referring to Article 69 for nomen- 
clature, 

10,300 
"^ ^o~ ^ 3.433 as before. 

The expression KG, whicli stands for 
the stiffness of the column, is made 



up of two parts, one above the floor, and 
one below the floor. 



For the former, K=6, C = 



7090 
150 



=4,700 
28,200 



whence KG = 
as in Article 69. 

Similarly the lower tier of 
column has KG = 28,200 

Hence the total KG, as affecting the 

joint between column and third floor 

beam is KG = 56,400. 

KG 56,400 

= 16-4. 



Whence 



B 3,433 

From Table II. Section 69, the mo- 
ment at the joint due to this is -072 Wl 
or M =-072 X 25,000 lb. X 300 in. = 
540,000 in./ll). 

Clearly half this moment is carried by 
the upper length of column, and half by 
the lower length, so that the section under 
tliird floor only carries M = 270,000. 

The stress due to tliis is -^ as in 

Article 69, and in our case, is 
270,000 X 8 
:^^^^~ = 305 Ib./in.^ 

so that the max. stress in 305 + 83 = 388. 
It will be seen that while the direct 
stress is double (as this lower column 
carries two floors instead of one) the 
bending stress is much reduced, and the 
total stress is less. If we investigate 
the stresses under the lower floor still, 
we shall find we get 

direct stress 1-24 5 

bending ,, 305 



4-'y5 
and so on. 

It will be seen from this that in outer 
columns, tlie stress is often greatest 
under the topmost floor or roof, and that 

191 



OSCAR FABER. 



iCDNCRETEJ 



the section required liere will also be 
strong enough for several tiers down, and 
in buildings of not more than six storeys, 
the outer columns are often with advan- 
tage made the same size from top to 
bottom. 

Even where a slight reduction of stress 
tempts a designer to vary the section, it 
must be remembered that a constant 
section enables the same column boxes 
or shutters to be used again, which is 
often a more important consideration 
than the saving of a few inclies of con- 
crete. 

The writer has just designed a large 
building in Shanghai where all the columns 
were 22 in. square from top to bottom, 
interior and outside alike. Not only are 
the column boxes used many times — 
saving time as well as money — but the 
beam boxes are also of the same length 
on all floors, whereas an alteration of 
size of columns involves making the 
beams a few inches longer on each suc- 
cessively higher floor. The only varia- 
tion was in adding a little more steel to 
the lower tiers of columns. 

• 71. In the case of interior columns, 
the bending generally plays a less impor- 
tant part. The Table of Moments in 
interior columns (Table III. par. 69) may 
be used, and it should be particularly 
noted that in this table IF is the live 
load only (since the dead load is balanced) , 
whereas for Table II. and outer columns 
IF is the total load, since both the live 
and dead load produce defiection and 
bending on the column. It must also 
be remembered that for interior columns, 
the condition for bending of columns is 
when one panel on one side is loaded and 
that on the other is unloaded, and under 
these conditions the direct stress on the 
column is of course less. Bending 
moments on interior columns may there- 
fore often be neglected without great 
risk, while in outer columns to do so is 
criminallv dangerous. 

72. Although the deflection of a beam 
causes bending in an outer column, and 
obviously increases the stress on the inner 
edge thereof, many structures have been 
designed and built without this bending 
stress having been allowed for. Of these 



structures a few have collapsed while 
others have stood. Of those that have 
stood, many have never had the loafl for 
which they were designed. Thus a bed- 
room 20 ft. X 10 ft. designed for 70 lb. 
per ft., is designed for 200 x 70 = 14,000 
lb. or 6i tons. It is never likely to 
carry more than 

4 people at i^ cwts. = 6 cwts. 

2 beds at ij cwts. = 3 cwts. 

other furniture, say 11 cwts. 

20 cwts. 
One ton as against 6-J- tons. 

There remain nevertheless certain struc- 
tures which have carried the load for 
which they were designed and yet were 
not calculated for bending in their col- 
unms. If these have stood well, and it 
can be shown that the actual stresses 
(calculated correctly) are considerably 
higher than usually allowed, then clearly 
these higher stresses were safe. 

Or otherwise put, if a column which, 
incorrectly calculated, appears to be 
stressed to say 500 Ib./in.^, is correctly 
calculated and shows 1,000 lb. /in.-, it 
obviously has not become less safe. More 
accurate calculations must stand for 
more economical, not more extravagant, 
structures, and obviously a more accurate 
system of calculation giving apparently 
greater stresses, must be accompanied 
by a raising of permissible stresses. 

Put 3'et another way, a nominal fac- 
tor of safety of four, which owing to 
elastic limit of steel and low strength at 
one month of concrete may be consi- 
dered to be a real factor of say 2J-, ob- 
viously contains a large margin. Part 
of this was to allow for errors of calcula- 
tion. Clearly, when one of the chief 
errors is eliminated, a lower factor is 
called for. 

The author is satisfied that when all 
secondary stresses are accurately cal- 
culated, stresses may be raised at least 
25 per cent, above those ordinarily used 
[20,000 steel and 750 concrete instead of 
16,000 steel and 600 concrete] not only in 
columns, but throughout the structure, and 
even then produce safer and stronger 
buildings than when lower stresses and a 
wrong system of calculation are adopted. 



192 



i 



CONSTRUCTICTMA 
ENGTNEfcglNG 



m 



REINFORCED COXCRETE ACID TOWER. 



A NEW REINFORCED CONCRETE ACID TOWER FOR 
THE RIORDON COMPANY, LIMITED, HAWKESBURY, 
ONTARIO, CANADA. 



The above building, of which we pubHsh illustrations, is for the preparation of 
acid for use in the paper mills. The building itself is principally interesting owing 
to the use of moving forms for the construction of the walls. This method, 
although almost universally used for deep bins in grain elevators, etc., in Canada 
and the United States, is not so well known in England. 




Fig. I. M . - I Ir - --- lit hlrection. 

Acid Tower, Hawkesburv Canada. 

The plan of the building consists of four circular concrete tanks, each 13 ft. 
external diameter with 9-in. walls, centre of tanks 22 ft. apart, height of tanks 
100 ft. from foundation slab ; above the tanks the outer quadrants were joined by 
straight walls and continued up for another 15 ft., making a total height of 115 ft. 

The central space, enclosed by the towers and curtain walls connecting adjacent 
towers, is used for a stairway and is divided into storeys by floors. The upper 
part of building above the top of tanks consists of two floors containing nests of 
pipes used in the manufacture of the acid. The four towers will be filled with, 
limestone rock which is fed in at the top of tanks and sinks down a few feet a 
day owing to the action of the fumes passed through it. 

Fig. I shows the moving forms in process of erection on the foundation slab. 
Pouring of concrete was commenced in these forms on October 8, 1920, and 
proceeded at an average rate of over 4 ft. per day up to the top of the buildings 
115 ft. above this point. 

193 



REINFORCED CONCRETE ACID TOWER. 



KKNteETEl 




Fig. 2. Towers in Course of Erection. 




Jlf^-v' I M-'^ 





Figs, s'and 4. View of Toweri 69 ft. above E1l\ U 



Fig. 2 shows the towers 17 ft. above foundation slab. 

Figs. 3 and 4 show the towers 69 ft. above foundation slab. 

I^'^g- 5 iP^^ge 196) shows the moving form work completed and the forms 
ior cornice partly erected. The moving form work 115 ft. above foundation slab 
was completed on November 5, or twenty-eight days from the commencement. 

The designs for the reinforced concrete of these towers were made by the John 
S. Metcalf Co., Limited, of Montreal, Canada ; this Company also carried out the 
•construction work. 



194 



1 



OON5TKUCT1CTM. 
ENGINEEitING 



iin 



USE AND ABUSE OF A CONCRETE STAGE. 



THE USE AND ABUSE OF A CONCRETE STAGE. 

A short article of interest appeared in a recent number of " Housing " under 
the above title. We would particularly draw aitention to the valvule suggestions 
contained in the latter part of this article. — Ed. 

If present intentions are carried out and a portion of our unemployed are drafted into 

the building trade, the concrete stage will play an important part in finding work for 

these men. Concrete work has often proved a failure, and many of these failures are 

due to the improper manner in which the materials have been mixed. To obtain good 

hand-mixed concrete the first consideration must necessarily be the stage, how, and of 

what size, to make it. 

The stage should be made up in sections and ledged together, the boarding or 

decking being grooved and tongued to prevent wastage of cement. In shape it should 



,v 



r; 



KofRT.'Ti^jrPI .-•-. (T«i>->i;=*<^ ^ R ATT SM 

./• i'ACCREGATE '.-.-i 



SIDE ELEVATION 
DCTAILS OP CAUCE^ BOX 



3ECTIO/M 
INCKEJIl b O I 

■■■■■■'■■'■■I |_ 



COMCR.ETE iTACt 



I'i. LEDQED BOARDING 




NOTE. A SMALLER CAUCE BOX 
OF PROPORTION ATE 5ITE TO BE 
US£D FOR CEMENT. 



CE ME/ST «? SHED* 





B 


• N 


S 





'■■■•■■■ 
FEET 



By courtesy of " Housing." 

resemble the letter Y, the wings of the Y being formed to allow a gauge box to be 
charged on each wing alternately. The stage should be placed on timbers or deals 
levelled on the ground. The length of the stage should be ample to give room for 
easy work and to keep a gang of concretors constantly employed. The length will 
usually be about 26 ft. over all, the width 8 ft., and the wings of the Y sufficiently 
long to take a 5 ft. 3 in. gauge box. The organisation rendered possible by laying 
down a stage of this kind very soon repays its cost. 

The gauge box should not be a large square box, a half-yard cube gauge will 
be found the most convenient for working, the size being about 5 ft. 3 in. X 3 ft. 
3 in. X 9i in. ; when in use, its length is laid parallel to the stage. A yard gauge 
will often intimidate the concretors, but a half-yard gauge is not so alarming. 

Tlie aggregate and sand should be at the wing end of the stage and as near it as 
possible. Tlie cement store should be placed between two heaps of aggregate and 
sand, as shown in the plan, the store being divided up into bins with a way through 
the centre. It is advantageous to unload the cement into bins because it is then 
easier to load the cement gauge box and the sacks can be returned in proper sequence 
immcdiatelv the cement is binned. 



195 



USE AND ABUSE OF A CONCRETE STAGE. 



[pgNCBETEJ 



The next consideration is the organisation of labour. The number of men 
required for mixing depends on the speed at which the mixed concrete is 
wanted ; but, assuming it is wanted at top speed, the following men will be re- 
quired : two to load the gauge box with aggregate, sand, and cement, eight to 
turn, and one to water the mixture. The gauge box should be loaded on one wing of 
the stage, and, while the mixture is being turned, the box is loaded on the other wing, 
and so on. The first pair of mixers will turn the concrete dry ; it is then again turned 
by the second pair ; the water is then added, the third and fourth pair turning the 
material wet to complete the gauging. The watering-pot should always be pro- 
vided with a rose, and the amount of water required for a gauging ascertained so 
that the concrete will all be of the right consistency. This method of mixing 
concrete has many advantages. The men always know their places, the gauge box is 
not too deep and allows a good area for spreading the cement, a shovel will pick up 
the whole depth at one operation, the concrete is on the move all the time and at 
the finish is properly mixed, accurate costings can be kept, and when the men have 
learnt the knack of turning the shovel correctly concrete can be cheaply mixed. 

Taking the other side — the abuse of the concrete stage. It often happens that 
the stage is made up of a few rough timbers laid carelessly on the ground ; this stage is 
usually far too small ; so many barrows of aggregate and sand are heaped on the so- 
called stage, a bag of cement is then placed on the top of the heap and the turning is 
begun, the water being thrown on by means of an ordinary bucket. 

As a result, a great portion of the cement is washed away and the proportions are 
in consequence something like 12 to i when they should be, say, 6 to i ; the concrete 
never is and never can be thoroughly mixed ; there is no room to prepare another 
gauging, so that half the men are idle ; concrete sacks get lost and are costly to replace 
at the present time ; and there are other evils too numerous to mention. 

Concrete well and properly mixed is one of the best of building materials. Concrete 
badly mixed is highly dangerous. 

E. J. I. 




Fig. 5. Moving Korinwork Completed. 
Acid Tower, Hawkesbury, Canada. 

{See page 193.) 



196 



o- oonstbucticmaD 



CEMENT NOTES. 



CEMENT NOTES. 

By Our Special Contributor. 



The "Killing" of Portland Cement. 

■" Killed " is the term used to describe 
concrete when the setting of tlie cement 
has been disturbed in such a way as to 
retard the hardening. 

Altliough the mechanism of the setting 
of cement is not a matter on which ex- 
perts agree, there is a fair consensus of 
opinion that the initial stages of setting 
are due to crystallisation, and upon the 
assumption that this is correct it is 
easy to imagine that when concrete is 
disturbed after setting has commenced, 
the interlocking crystals, causing the 
stiffening of the mass known as initial 
set, become broken up and possibly 
partially re-dissolved so that a new for- 
mation of crystals is necessary before 
setting can proceed. This takes time 
and thus leads to retarded hardening. 

In some cases, however, it happens 
that a " killed " concrete remains per- 
manently deficient in strength, and this 
may occur when frost intervenes and 
causes a further disintegration of the 
crystalline formation, or when through 
lapse of time the amount of water in 
the concrete required to complete the 
hardening has disappeared through evap- 
oration or absorption. This possibility 
emphasises the desirability of keeping 
concrete moist for a week or so after 
laying. 

The fact that concrete is being " killed " 
is always apparent to an intelligent work- 
man engaged in the mixing and laying 
of the concrete, but is not always re- 
vealed to the man in charge. 

It is usually a difficult matter to prove 
from an examination of concrete that 
" killing " is the cause of lack of strength, 
and concrete failures are frequently 
attributed to this cause only after a 
process of elimination of other causes. 
A concrete expet-t can, however, in some 
cases recogniss a characteristic appear- 
ance of " killed " concrete. 

Prevention of " killing " is of course 
better than cure, but it may be useful 
to mention here that " killed " concrete 
can frequently be improved by appli- 
cations of a solution of silicate of soda. 
Killing " may of course be prevented 
by completing the mixing and deposition 
of concrete before setting commences. 



and here it becomes necessary to define 
the period known as commencement of 
set. 

The initial set as defined by the Bri- 
tish Standard Specification implies that 
the cement has acquired a certain con- 
sistency sufficient to resist the penetra- 
tion of a needle of definite weight and 
dimensions, but every cement tester 
knows that the actual setting as evi- 
denced by stiffening — probably crystalli- 
sation — commences some time before 
the initial set as recorded under British 
Standard Specification testing condi- 
tions. 

It is not uncommon to find cements 
having British Standard Specification 
initial sets of 90 minutes coupled with 
final sets of 150 minutes, and although 
cement manufacture has made advances 
in recent years there are few who would 
claim that these figures truly represent 
the commencement and finish of setting. 

The fact is that British Standard 
Specification tests are founded on an 
arbitrary basis and are doubtless the 
best standard that can be devised with 
present knowledge, but in the writer's 
view it is unwise to accept the initial set 
period as the permissible time for mixing 
and depositing concrete. 

When weak mixtures of concrete are 
used in the open air during cold weather, 
it is probable that the British Standard 
Specification initial set period is a safe 
one because the actual setting test is 
made at a minimum temperature of 
58° F., and with the minimum propor- 
tion of water to produce plasticity, 
whereas the lower external temperature 
and the larger proportion of water used 
in practice, especially with weak mix- 
tures, both tend to retard the commence- 
ment of setting. 

But the conditions are reversed in the 
summer, and the risk of relying upon the 
B.S.S. initial set test then becomes a 
serious one. 

There is, however, another aspect of 
the " killing " of cement which must be 
considered, and this is that large amounts 
of concrete have been placed, in which 
the cement has been " killed " without 
any apparent disadvantage. Cement 
made by the chamber kiln process some 

197 



CEMENT NOTES. 



[CQNCRETEl 



jRfteen or twenty years ago frequently 
had an initial set of ten minutes or less, 
and in the early days of rotary kiln 
manufacture great difficulty was experi- 
enced in producing a cement with more 
than five minutes initial set. 

With such setting qualities it was prac- 
tically impossible to avoid " killing " the 
cement, and it is no exaggeration to 
state that hundreds of thousands of tons of 
quick setting cement have been " killed " 
in use without any apparent harm. 

Laboratory tests can be cited which 
demonstrate that under certain condi- 
tions " killed " cement is as good as 
cement properly used, and an illustra- 
tion can be given by quoting the follow- 
ing tests given by Candlot in his Ci- 
ments et Chaux Hydrauliques : — 

Tensile strength at seven days of a 
mixture of three parts sand to one part 
cement : — 

Normal mixing — 19-5 kilos, per sq. cm. 
= 277 lb. per sq. inch. 

" Killed " mixture — 22'2 kilos, per sq. 
cm. = 315 lb. per sq. inch. 

The conditions under which cement 
can be " killed " without harm have 
still to be determined, and in the mean- 
time the user of cement would be well 
advised to avoid "killing" by placing 
his concrete as soon as possible after the 
cement comes into contact with water. 
Inter alia, this implies that cement and 
damp aggregate must not be in contact 



until required for conversion into con- 
crete and that no mixed concrete should 
be allowed to stand during workmen's 
meal-times awaiting deposition. 

Portland Cement V. Lime. 

The relative values of Portland cement 
and lime is a subject of perennial discus- 
sion among engineers. In the end, the 
prices and availability of the two materials 
usually decide the question as to which 
should be adopted for mortar-making 
purposes. 

Price alone is however not a fair cri- 
terion on account of the greater strength 
possessed by cement mortars above lime 
mortars, and in some results published in 
Germany, the factors of price and strength 
are both taken into account by adopting 
as a comparison a simple fraction of 
which the strength of a brickwork pier 
in kg. per sq. cm. is the numerator and 
the cost of the structure per cubic metre 
is the denominator. By constructing 
and testing brickwork piers with cement 
mortar and with lime mortar some in- 
teresting figures have been obtained. 

If ordinary lime mortar (one lime to 
three sand) be taken as unity, cement 
mortar (one cement to four sand) gives 
in the above fraction the figure 2' 12, thus 
showing that cement mortar can be used 
to considerably greater advantage than 
lime mortar taking both cost and strength 
into account. {Engineering Abstracts.) 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books which have appeared during 
the last few months. 



Handbook of Building Construction. 2 vols. 
Editors-in-chief: George A. Hool and 
Nathan C. Johnson. Publishers: Messrs. 
McGraw-Hill Publishing Co., Ltd., 6 £) 
8 Bouverie Street, E.C4, and New 
YorR, U.S.A. 

Price £3 the two vols. 

These two volumes bound in flexible 
leather, clearly printed and well illus- 
trated, predispose the reader to a satis- 
factory judgment, and after a closer 
acquaintance, one's only regret is that 
they are based on United States practice 
and are not universally applicable to the 
requirements of the British reader. 

As a handbook of building construc- 
tion, the work is most comprehensive, 
and in some sections exhaustive, so that 

198 



one envies his American confrere who can 
have such a mine of information by his 
side. 

The first volume commences with the 
elements of structural theory and sets 
out clearly the principles involved in 
calculating strengths of beams, columns, 
trusses, etc., in timber, steel and con- 
crete. This section should be of con- 
siderable benefit to the student and to 
the practical man who has not had the 
advantage of a technical education but 
is willing to take pains to learn first 
principles. Then follows a section on the m 
designing and detailing of structural ■ 

members including adequate treatment 
of reinforced concrete. _ 



E 



OONSTBUCnONALl 
ENGTNEEJgXNG ^-'i 



NEW BOOKS. 



Succeeding sections give a wealth of 
structural data covering nearly 500 pages 
and providing much detailed information 
respecting foundations, piling, floors, roofs, 
chimneys, etc., and then specialising into 
the design of public and industrial build- 
ings, farms, etc. Methods of construc- 
tion and construction equipment are 
discussed and well illustrated, followed 
with a section on building materials con- 
taining admirable articles on concrete 
and concrete aggregates by Nathan C. 
Johnson, whose name is familiar to readers 
of this Journal. 

Estimating and contracting are some- 
what briefly dealt with in fifty pages, and 
the work concludes with some 300 pages 
on mechanical and electrical equipment 
of buildings, including water supply and 
sewage disposal. 

The volumes have been compiled by a 
staff ■ of forty-six specialists, and the 
name of the writer is given over each 
section. With so many contributors 
on similar subjects it is difficult to avoid 
inconsistencies ; thus on page 610 it is 
stated that " the use of solid concrete 
for walls above grade is not generally con- 
sidered advisable on account of . . . the 
tendency of concrete to absorb moisture 
and cause damp walls on the inside," 
while on p. 685 occurs the statement that 

reinforced concrete is the most suitable 
material for many retaining walls because 
of the possibility of making it moisture 
proof." 

As already indicated, the value of the 
liandbook to the reader in this country 
is reduced on account of the materials, 
viz., timber and various machines and 
fittings being those common in America 
but not in the I'nited Kingdom, while 
the rules and formuhc relating to rein- 
forced concrete and other constructional 
work are those drawn up by American 
Authorities, and although quite satisfac- 
tory in their way, they cannot be adopted 
by the British engineer, who must neces- 
sarily obey the rules and customs existing 
in his own land. 

In some respects the handbook is an 
encyclopedia, and the wisdom is rather 
doubted of attempting to .set out in 
thirty pages not only electrical theory, but 
a description of electrical wiring wiiich 
may induce an amateur to undertake 
work which siiould only be executed by 
one with expert knowledge. 



Similar comments might be made on 
the sections on boilers and chimneys, 
while in the water supply section only 
one of the numerous water softening 
methods is discussed. 

Concrete receives the full treatment its 
importance deserves in the handbook, 
but the section on cement might well be 
revised by a cement manufacturer before 
the next edition is published. Such a 
revision would result in the paragraph on 
seasoning of cement being deleted, for 
such treatment should now be quite un- 
necessary. Also, Portland cement is 
not burnt " to a point somewhat beyond " 
the commencement of fusion, while 

steel Portland cement " is probably 
intended to mean " eisen " or " iron 
cement," which is Portland cement 
(produced partly from slag as a raw 
material) with slag as an adulterant. 

In the paragraph on concrete pile 
foundations, a reference is made to piles 
containing less cement than one part 
cement to two parts sand as being suscep- 
tible to frost, and it is not clear whether 
this is an error or whether coarse aggre- 
gate in addition to the sand is implied 
but not mentioned. 

These small defects do not detract 
from the value of the handbook as a 
whole, and indeed it would be surprising 
if in a work of 1400 pages it were not 
possible to indicate one or two possibili- 
ties of improvement. 

Subject to the limitations imposed by 
its American origin, the handbook can be 
recommended as a most useful work of 
reference to all concerned in construc- 
tional work. 

" Tonindustrie Kalender, 1921." 

The" Tonindustrie Kalender " for 1921 
presents its usual appearance and con- 
tains the same general information as 
usual. The new matter consists of a 
rather more lengthy " Table of Purposes 
for which Seger Cones may be used," a 
description of the Hirsch electric furnace 
for determining sintering and fusion 
temperature, a glossary of materials used 
in the cement and other clayworking 
industries, and a Table siiowing the 
temperatures attained in industrial 
furnaces. 

Tiie greater part of the Kalender is 
occupied by a useful " Buyers' Guide " 
which covers nearly zoo pages. 



199 



THE "TONKIN" MIXER. 



[CQNCRETEl 



A NEW CONCRETE MIXER. 
THE ♦♦TONKIN" MIXER. 

The necessity for good concrete, and tlie hict tliat the mixing operation is one of the 
vital factors in the prodnction of good concrete, have been consistently urged by the 
professional and research bodies, and are now realised by all who have the interests 
of soundly-constructed concrete buildings at heart. It is also generally realised that 
a much better result is obtained when the materials are mixed by machine than 
when the costly and uncertain method of hand-mixing is adopted, and of late years 
considerable headway lias been made in the design of concrete mixers, chiefly, however, 
of the revolving drum type. 

We recently had an opportunity of seeing in operation a mixer designed on an 




Fig. I. The Tonkin Mi.xer. 



entirely new principle, the invention of Mr. G. A. Tonkin, which has been put on the 
market by the Tonkin Mixer Company, of 608, Salisbury House, London Wall, E.C. 
Mr. Tonkin, who is also the inventor of the well-known " Australia " concrete block- 
making machine, has had considerable experience of concrete work, and realises that 
one of the first essentials of machinery to withstand the wear and tear of use on a build- 
ing contract, and which is to be liandled by unskilled labour, is simplicitj'. 

As will be seen from the accompanying illustrations, the machine has very few 
working parts. The materials are mixed by two revolving rakes attached to an axle 
set horizontally across tlie drum, and so arranged that when revolving they follow 
each other on the worm principle, turning the materials from the ends of the drum 
to the centre. At each revolution, therefore, the whole of the contents come together 
in the centre and drop to the bottom of the drum. The rakes revolve at the rate 
of twenty-five times per minute, and a dozen revolutions are sufficient to mix a 
batch ; every particle contained in the drum is turned, kneaded and raked at every 
revolution, and the result is a very thorough mix. The materials are in view during 
the whole of the operation, and as the mixing process can be observed during the 
whole of the period there is no possibility of their being discharged before a satis- 



r o, CONSTBUCnOMAJ 



THE "TONKIN" MIXER. 



factory mix is obtained ; neither, on the other hand, is there any possibihty of time 
being wasted by over-mixing. 

The materials are tipped into tlie drum from a hand-barrow running up an inchned 
track on the engine side of the machine, and discliarged from the other side. The mix 
is discharged by tipping the drum by means of a small winch at the opposite end to 
the drive {Fig. 2 shows the machine in the discharging position). The rakes revolve 
from the back (or discharging side) of the drum to the front, and help to clear the drum 
when it is tipped ; there is no necessity to stop the machine while it is being discharged, 
and thus a continuous output is maintained. 

The machine has a capacity of three cubic feet per batch, and without the power 
drive, but fitted with a handle at each side, is a cheap and efficient means of mixing 
concrete for even the smallest job. With the power drive, and by reason of its con- 
tinuous operation, it has a very large output, and we are informed that one working 




Fig. 2. The Tonkin Mixer. 



on the construction of a large reinforced concrete building in London is turning our 
go cub. yds. of concrete per eight-hour day. It can also be used for mixing other 
materials, and several are now in use by local authorities for mixing road materials — 
it is specially suitable for mixing tar macadam. 

The " Tonkin " mixer will go a long way towards overcoming the objections 
sometimes lieard that the output of small concrete mixers is proportionately small, 
and that the large mixers are so complicated as to require skilled supervision, are costly 
to buy and to run, and difficult to transport from one site to another. 

The machine, complete with oil engine, is at present sold for /loo ; with power 
attachments, but without engine, the price is /60 ; and fitted witli a handle at each 
side for hand operation, the price is /50. The cost of renewals should be extremely 
low ; with the exception of the engine and drive the only parts subject to any large 
amount oi wear are tlie teeth on the rakes, and these can be renewed separately as 
re(|nired. 

Composite Concrete Construction Company. —We are asked to state that the address 
of this firm is 51, I'all .Mall, .s'.H'.i, and not, as stated in our l'>bruary issue, 1 1, Puke 
Street. 

F2 20I 



MEMORANDA ^ 



[QQNCBETEJ 




Memoranda and Neivs Hems are presented under this heading, with occasional 
editorial comment. Authentic news voUl be welcome. — Kd. 



ROAD NOTES. 

Road Constructional Requirements from the User's Point of View. — In the course 
of a lecture recently delivered to graduates and students of the Institute of Transport, 
Col. Bressey, Divisional Engineer, London Roads Branch, Ministry of Transport, 
said : 

The modern user of highways naturally expects, in return for his contribution 
towards the cost of road upkeep, that his requirements shall be borne in mind in the 
design of new and the improvement of old highways, the present condition of which, 
in his eyes, leaves much to be desired. 

In the forefront of the motorist's grievances one may probably place the perpetual 
interruptions of traffic caused {a) by the opening of streets, and [b] the renewal of 
road surfaces, the former arising from the multitude of mains, conduits, sewers, drains, 
etc., buried under the paving, and the latter from the use of insufficiently durable 
materials. The two causes are. however, closely interrelated, for, however great the 
precautions adopted in making good the trenches cut in a road, a weak spot is almost 
invariablv left, wdiich shortens the life of the paving. Indeed, it may be questioned 
whether in the narrow streets of busy towns the materials used for paving are ever 
given a fair chance of displa^dng their durability, owing to the perpetual excavations 
to which the streets are subjected. Much might be done to mitigate this annoyance. 

The gradual replacing of waterbound macadam by surfacing materials of greater 
durabilitv is proceeding apace, and tlie recurrent renewals of road crusts are therefore 
taking place at longer intervals. 

Owing to the rising cost of labour, local authorities fortunately show an increasing 
preference for permanent materials which occasion a minimum of wage expenditure 
for scavenging and upkeep. 

The reduction of tractive effort by the adoption of a smooth, even surface is of 
high importance to road transport, and the avoidance of steep gradients is an almost 
equally weighty consideration. A maximum gradient of i in 30 is often quoted for 
non-mountainous districts, and a minimum gradient of about i in 250 is desirable 
for the proper drainage of the road. The camber, or convexity, of the carriageway- 
should not exceed i in 30, and where there is a longitudinal gradient the camber may 
be reduced to a much lower figure. American engineers are in many cases adopting 
a scarcely perceptible camber for the new concrete roads to which so much attention 
is now being devoted. 

Easy curves are essential ; an ideal often quoted by engineers on the Continent 
is a minimum radius of 550 yards, although in many hilly districts where hairpin 
bends are inevitable a radius of only 100 ft. is found. 

For the safety of traffic, an unobstructed sight line of at least 100 yards is recom- 
mended, and this consideration implies tlie smoothing out of gradients at summit 
point on hilly routes. 

Bath's Concrete Roads. — The General Purposes sub-Committee reported that, in 
view of the sanction of tlie Ministry of Health to the construction of the reinforced 
concrete roads at London Road and Lower Bristol Road, to which they would con- 



[&ga?.^^'fcr!.^^ MEMORANDA. 

tribute half the cost, it was recommended that arrangements be made that Mr. E. 
Ireland lay reinforced concrete in these roads on the same terms that he was now laying 
concrete in the Lower Bristol Road. 

Mr. Sealey asked if the Committee had received any report as to the wear of the 
reinforced concrete, which was new to them. 

The Chairman replied that the Surveyor recommended it, and he (the Chairman) 
did not think there was any question about the wear. 

The City Surveyor was asked to give his opinion. He said they had no actual 
report from other towns, but experience proved that reinforced concrete was satis- 
factory. 

Reinforcement of Concrete Roads in California. — In reinforcing some of the concrete 
roads in California what is known as the two-operation method has recently been 
applied. A mesh reinforcement is used and the operation is as follows : — • 

The mesh is shipped to the job in fiat sheets cut to the proper length. Mixing 
operations are then begun and the lower half of the slab is poured for a convenient 
length (section one). Where a spout mixer is used this first pouring is from the end 
of the spout. A gate in the middle of the spout is then opened and the space next the 
mixer (section two) is poured on the sub-base in the same manner. During this second 
operation the fabric is laid on section one and, without moving the mixer, the top half 
of section one is poured over the mesh from the outer end of the spout. 

The mixer is then advanced a distance equal to the length of a section and while 
the lower half of section three is being poured from the gate in the middle of the spout, 
sheets of fabric are laid over the lower half of section two. The gate in the middle of 
the spout is then closed and the fabric of section two is covered with its top layer of 
concrete by pouring from the end of the spout. This process is repeated during the 
remainder of the job, two adjoining sections of half thickness, one at the top and one 
below, being poured from each mixer position. — Engineering News Record. 

Another method recently adopted on forty miles of concrete road was the follow- 
ing : — In this case J in. deformed steel bars were used, placed transversely on i8 in. 
centres. It having been found, on California highwavs, that triangular sections will 
ravel out readilv where transverse cracks reach the edge of the road, these points are 
strengthened by using longitudinal runs of f in. bars, laid with the joints alternately 
butted and lapped and butt joints brought half way between the adjacent transverse 
bars. 

In placing these bars so that they are supported at the proper height from the 
subgrade, short lengths of pipe are used. As the concrete is poured the pipes are 
withdrawn. These sections of pipe are fastened to the concrete mixer by a wire or 
chain and as the mixer moves along the pipes are pulled along with it. Hooks hung 
on the headers or short pieces of 2 by 4 in which a slot is cut for holding the rods at the 
proper height and distance from the edge of the pavement support the longitudinal 
rods during the pouring of the concrete. As the paving progresses the wood blocks 
may be moved along. The end of the transverse bars are bent and hooked over the 
longitudinal bars where they are securely tied. Four sections of pipes in a rigid fan 
shape hold the rods in position while pouring the concrete on wider pavements than 
the standard. 

GENERAL NOTES. 

Cement Linings of Water Flumes. — Some experiments carried out in connection 
with the water Humes, or wooden distribution troughs, on tlie Waterford (U.S.A.) Irriga- 
tion District have convinced the authorities that a considerable saving in both initial 
cost and maintenance charges can be effected by the u.se of cement linings to the flumes, 
and such satisfactory results have been obtained that the system is to be extended. 
,\ wire mesh is placed along the bottom and sides of the flume, and kept about f in. 
from the timber. On this mesh a cement plaster is coated to a depth of one inch, 
tiie plaster consisting of one part cement and three parts sand. In the case of 
flumes where the timber is decayed the insertion of such a lining would be considerably 
cheaper than renewing the timbers, and in the case of new flumes a much lighter 
timber construction can be used. As a result of the experience gained it is 
recommended tliat exjiansion joints be jirovided to allow of not onlv the expansion 

203 




CONSTRUCTIQNAJ^ 
EJ^GINK^ERTNG 



CONCKEJX^J 




STOP WASTE! 

"ZENITH'' PLANTS 

— ARE THE MOST EFFECTIVE — 

ANTI = WASTERS 

THE ENGINEER OR CONTRACTOR 
CAN FIND ON THE MARKET, 



THE "ZENITH" FRICTION WINCH 

For Steam, Petrol, or Electric Drive. 

THE "ZENITH" CONCRETE MIXER 

Arranged for any Form of Drive. 

THE "ZENITH-PUP" CONCRETE MIXER 

For Small Users. 



ALL INTERESTED 

In carrying out their Contracts in the most Efficient and 
Economical manner, should write for the following catalogues : — 

No. 80. Steel Sheet Piling. 

No. 81. Pile Hammers and Complete Driving and 

Withdrawing Equipment. 
No. 82a. "Zenith" Friction Winches. 
No. 70. "Zenith" Concrete Mixers. 
No. 82. "Zenith-Pup" Concrete Mixers for Small 

Users. 



THE BRITISH STEEL PILING CO. 

DOCK HOUSE, BILLITER STREET, LONDON, E.C.3. 



Please mention this Journal when writing. 
204 



\E 



CONSTEUCnONAL 
ENGTNEEJglNG — ; 



MEMORANDA 



and contraction of the lining, but also for the expansion and contraction of the wood 
to which the lining is attached, which will, of course, be more variable in movement 
than the cement. In the tiumes built on this sytem no longitudinal cracks have 
appeared. 

Concrete Chimneys. — Several large reinforced concrete chimneys have recently 
been completed in tlie United States, in which a novel form of construction has been 
adopted. From a brief account before us, it appears that a steel mast is first erected to 
the required height and the chimney built around it. The mast carries a working 
platform, which is raised as the work proceeds, and also radiating steel tees by wliich it 
is possible to preserve the lines of the chimney and vmiformit}- of taper. The shuttering' 
is of sheet steel with angles made to overlap as the diameter of the chimney decreases. 
No scaffolding either inside or outside the stack is used. It is stated that the system 
considerably reduces the cost of construction. An in.stance is given of a stack 5 ft. by 
4 ft. by 100 ft. being completed in twenty-one days by four men. 

Gas Engine E^aust Silencer. — A novel use for concrete which has given satis- 
factor\' results is represented by the construction of an exhaust silencer for a large 
gas engine installed for pumping at one of the wells of the Standard Oil Co. in the 
United States. The silencer is described as a concrete chamber 4 ft. square by 8 ft. 
deep, with the top sloping inwards and leaving an opening about 8 in. square. The 
chamber is embedded in the ground about 5 ft. below the surface. Exhaust gases 
from the engine are led into the chamber through an underground pipe connected 
near the bottom of the silencer, the exhaust escaping through the top opening ^^^th 
very little noise, as the concussion of the explosions is absorbed by the concrete and 
the solid backing of earth on all sides. It is stated that gas engines with concrete 
silencers can be installed quite close to offices and dwelling-houses without causing 
any nuisance, and that the cost of constrviction is ver^- much less than that of metal 
or timber silencers, particularh- in places where sand and gravel are found on the 
site. 

A Concrete Coaster Launched at Preston. — Tlie concrete ship Buvscough, the first 
of two being built by the Ritchie Concrete and Engineering Shipbuilding Co., Ltd., 
at their yard on the Ribble, has been successfully launched at full tide. The two 
vessels are for Messrs. Tyrer's Coasters, Ltd., of Liverpool and Preston. The Burs- 
cough has been built on the Ritchie United System of reinforced concrete construc- 
tion and has a length of 124 ft., width 23 ft., and moulded depth 12 ft. She will have 
a load draught of 10 ft. 6 in. Her registered tonnage is 143, and the dead-weight 
carrying capacity 300 tons. She is designed for a speed of nine knots, fully laden, at 
sea, being a single screw ship fitted ^\ith internal combustion marine oil engines of 
240 brake horse-power. Accommodation for the personnel of the ship is afforded on 
the deck level. 



The International Building Trades Exhibition. 

this Exhibition tliis \-ear arc the following : — 



-Among the firms exhibiting at 



Associated Portland Ce- 
ment Manufacturers, 
Ltd. 

Australia Concrete 

Block- Making Ma- 
chine Syndicate, Ltd. 

British Everite & As- 
bestilite Works, Ltd. 

British Fibrocement 
Works. 

British Portland Ce- 
ment Manufacturers, 
Ltd. 

British Rof>ting Co. 

Britisii Steel Piling Co. 

Builders' & Contrac- 
tors' Plant, Ltd. 

Building Products, Ltd. 

Cement Marketing Co., 
Ltd. 

Climbing Steel Shutter- 
ing Co. 



Concrete Dwellings, Ltd. 
Crittall Mfg. Co., Ltd. 
Edwards Construction 

Co., Ltd. 
Expanded Metal Co., 

Ltd. 
I'awcett Construction 

Co., Ltd. 
l'"eroda, Ltd. 
Fireproof, Ltd. 

F. McNeill & Co., Ltd. 
Grovcsend Steel & 

Tinplate Co., Ltd. 

G. K. Speaker & Co. 
Hayter, Ltd. 
Heiuy Wilde. 
Ironite Co., Ltd. 
Jf)hnson's Reinforced 

Concrete Engineering 
Co., Ltd. 
Kemer - Greenwotid, 
Ltd. 



Kleine Patent Fire Re- 
sisting Mooring Syn- 
dicate, The, Ltd. 

Liner Concrete Machin- 
ery Co. 

Manelite Patent Con- 
crito Machinery Co., 
Ltd. 

Metacon Patent Glazing 
Bar Co., Ltd. 

Modern Building Co. 

Moler I'"irepn)()f Brick 
& Partition Co., Ltd. 

Ransome MachiiiervCo., 
Ltd. 

Kawplug Co., Ltd. 

R. G. Wliittakc:. ltd. 

R. H. Kirk & Co. 

Ruberoid Co., Ltd. 

R. W. Blackwell \ Co., 
Ltd. 



Self-Sentering Expan- 
ded Metal Works, 
Ltd. 

Sharp, Jones & Co. 

Sieg^vart Fireproof 

Floor Co., Ltd. 

Stothert >.S; Pitt, Ltd. 

Sutcliffe, Speakmim & 
Co., Ltd. 

Thermos Flooring Co , 
Ltd. 

Torbav & Dart Paint 
Co., Ltd. 

Tourba Construction 
Co. 

Tuke \- Bell, Ltd. 

WiltlevCo.,Ltd. 

Winget, Ltd. 

Wm. Bayliss.S: Co., LtiL 

Wm. Kennedy. 



-J05 




concke.te:«^^^£^^- 





THIS illustration shows one of 
our concrete distributing plants 
designed to serve an area of lOO feet 
radius. The chuteing is divided 
into two sections, the outer section 
being balanced. By this means it 
is possible to deliver the mixed con- 
crete anywhere within this radius, 
speedily and with a minimum of 
labour and effort. This distributing 
plant greatly simplifies the erection 
of large buildings and engineering 
works, and renders considerable 
economies possible. 

THE plant illustrated here is now 
in course of construction to the 
order of a client. 

PARTICULARS of this plant and 
of the " Victoria " Concrete 
Mixers to use in conjunction with it' 
will gladly be supplied on request. 




STOIHEJIlLPITr 

(MIXER DEPARTMENT) 

1 I.VICTORIA ST.. LONDON S.Wl 



206 



Please mention this Journal when writing. 



t^^?.^ST;.^^J MEMORANDA. 



Queensland's New State Cold Stores. — Among the public works in course of con- 
struction in Queensland are the State Cold Stores at Hamilton, on the Brisbane 
River, at an estimated cost of £249, ooo. The building is being constructed of rein- 
forced concrete on concrete piles. The cold stores consist of two floors, the ground 
floor being divided into nine butter rooms, with a storage capacity for 150,000 boxes. 
On the upper floor are five cheese rooms, with a gross content of 158,400 cubic feet, 
and a storage capacity of 25,000 crates; and four fruit and egg rooms, with a storage 
capacity of 38,400 cases. This floor is to be worked by elevators from the railway 
platform and by gravity chutes to ships' holds. The insulation is to consist of 2 in. 
cork board manufactured at Brisbane from imported Spanish granulated cork. 

Scientific and Industrial Research. — The Lord President of the Council has estab- 
lished an Inter-Departmental Committee on Patents with the following terms of 
reference : — 

1 . To consider the methods of dealing ^^ith inventions made by workers aided or 
maintained from public funds, whether such workers be engaged [a] as research 
workers, or (6) in some other technical capacity, so as to give a fair reward to the 
inventor and thus encourage further effort, to secure the utilisation in industry of 
suitable inventions and to protect the national interest ; and 

2. To outline a course of procedure in respect of inventions arising out of State 
aided or supported work, which sliall further these aims and be suitable for adoption 
by all Government Departments concerned. 

The Secretary to the Committee is ^Ir. A. Abbott, to whom all communications 
should be addressed at 16 and 18, Old Queen Street, Westminster, London, S.W.i. 

CONCRETE AND HOUSING SCHEMES. 

Beeston. — T.he Beeston Urban District Council is considering the erection of 
fifty concrete houses, at a cost of ;^9i8 each. 

Chirk. — At a meeting of the Chirk Rural District Council, the Engineer stated 
that by the use of direct labour, and concrete or local stone, a saving of about ;/^2oo 
per house could be effected in the Council's housing scheme, as compared witli the 
usual methods of construction. 

London. — The London County Council has sanctioned the purchase of three 
" Winget " machines for the manufacture of concrete blocks on the Becontree 
liousing site. 

Musselburgh. — Owing to the high cost of the houses to be built in connection 
with tlie Musselburgh Borough Council's housing scheme, it has been decided to secure 
an economy by the use of concrete blocks in place of bricks, instead of reducing the 
number of rooms per house. 

Newport. — The Newport Town Council has decided to put in hand as soon as 
possible the erection of a further 147 concrete houses on the Somerton housing estate 
on the " Duo-slab " system. 

Oxford. — The Oxford Housing and Town Planning Committee has instructed the 
City Engineer to proceed with the construction of two concrete houses on the Botley 
Road site, and has recommended the City Council to acquire a site at the corner of 
]3otley Road and Ferry Hinksey Road on wliich to build concrete houses bv public 
tender. 

Willesden. — The Engineer to the Willesden I'rban District Council has submitted 
a favoural)le report to the Council on the concrete houses, on the " Fidler " svsteni. 
recently completed for the Hayes Urban District Council, and tlie Willesden Council 
is considering the erection of similar houses in its own area. 

Stanford-le-Hope. — The Orsett Rural District Council has decided to erect 100 
concrete hou.ses at Stanford-le-Hopc. 

NEW METHODS AND MATERIALS. 

The following is a further list of materials and new methods of construction 
approved by the Standardisation and Constructit)n Committee: — 

207 



MEMORANDA. [CONCRETEJ 

The Weardale Steel, Coal and Coke Co., Ltd., Jhornley Colliery, Co. Durham. — The " Hoop " Prin- 
ciple of Reinforcement for Concrete Houses. — The " Hoop " Principle of Reinforcement for Monolitliic 
concrete walls is composed of 3 ft. by i in. by ,'.; in. octagon hoops, with angle stanchions, 6 ft. by 
J in. fixed between each hoop, forming a tie for the clinker blocks of the inner lining. 

By this method of construction, all doors, windows and floor joists can be erected on the hoop- 
framing before concrete work is started. 

R. L. Bendall, 14, Richmond Wood Road, Bournemouth, Hants. — The Bendall Walling:. System. — 
With this system it is possible to construct the walls with concrete without timber shuttering, and, if 
necessary, witli unskilled labour, by facing the exterior with clay or concrete tiles and the interior with 
clinker slabs tied together with high tensile steel wires, the cavity being filled with wet concrete. 

W. McLeod, cjo Bank of New Zealand, 1, Queen Victoria Street, London, E.C.4.- — A system of walling 
consisting of thin bottomless boxes of concrete or burnt clay. The main units are 12 in. long and 
5 in. high, and of three thicknesses — 4.^ in., 7 in. and 9 in. These are laid breaking bond on top of each, 
other without mortar and filled in solid witli wet concrete. 

PROSPECTIVE NEW CONCRETE WORK. 

Amm.\nford.' — The .\mmonford I'rban District Council is considering the erection of a new bridge,, 
at a cost of £20,000. 

Birkenhead. — The Birkenhead Corporation has received sanction to the borrowing of ^120,000 
for extensions to the waterworks. 

Bo' N ESS. — The Bo'ness Town Council is considering the construction of a wharf on reclaimed land 
from Bo'ness to Grangemouth, at an estimated cost of £3,000,000. 

Buckie. — The Buckie Town Council has received Treasury sanction to the borrowing of £50,750 
for the Harbour Extension Scheme. 

Burnley. — ^The Burnley Corporation has applied to the Ministry of Health for sanction to a 
loan of £50,000 for the construction of a new reservoir at Hurstwood. 

Dublin. — ^The Dublin Harbour Commissioners are considering the erection of a grain silo at the 
Harbour. 

Dufftown. — The Dufftown Town Council is considering plans submitted by Mr. Wittet, of Elgin, 
for a new 17,000-gallon reservoir. 

Guildford. — The Guildford Towti Council is considering the construction of a reinforced concrete 
open-air swimming bath, at a cost of £8,000. The plans are for a pool 120 ft. by 45 ft. with pay office, 
attendants' room, etc. 

Ilford. — The Ilford Urban District Council has passed plans for the construction of a reinforced 
concrete coal store on the banks of the river Roding, for the Ilford Gas Company. 

Liverpool.- — The Liverpool Corporation is considering the acquisition of 45 acres of land adjoining 
the Corporation's existing reservoirs at Prescot for the provision of a new reservoir. 

Newquay. — The Newquay Urban District Council has decided to construct a new swimming bath. 

Penwith. — The West Pen^\ith Rural District Council has applied to the Ministry of Health for 
sanction to the construction of a new reservoir at Carbis Bay, at a cost of £6,000. 

Salford. — The Salford Corporation has decided to proceed with a scheme of improvement and 
extension at the sewage works at Weaste, at a cost of £250,000. 

Wick. — ^The Wick Harbour Trust is considering a scheme for the improvement of Wick Harbour, 
including the construction of two large breakwaters, at a total cost of about £1,000,000. 

TENDERS ACCEPTED. 
Concrete Houses. 

Annfield Plain. — The Annfield Plain U^rban District Council has entered into an agreement with 
Messrs. William Airey & Son, Ltd., of Leeds, for the construction of concrete houses, on the " Duo- 
Slab " system. Under the agreement, the Company will receive a royalty of £5 per house for the 
first 100 houses and £3 per house in excess of that number. 

BooTLE. — The Bootle Town Council has accepted the tender of Messrs. R. Costain & Sons for the 
erection of 212 concrete houses at a total cost of £205,440. 

Leeds.- — The Leeds Corporation has accepted the tender of Messrs. William Airey & Sons, Ltd.,. 
of Leeds, for the erection of 170 concrete houses at £835 for Type " A " houses and £950 for Type " B " 
houses. 

Thornaby. — ^The Thomaby Town Council has provisionally accepted the tender of the Ben Baine 
Constructional Co. for the erection of five pairs of " B4 " type houses on the " Lean " system, at £2,130 
per pair. 

Torquay. — The Tov\-n Council has accepted the tender of Messrs. W. H. Smith for the erection of 
40 non-parlour type concrete bouses at £882 each for houses built in pairs and £81 5 each fdr houses buQt 
in blocks of four. 

General. 

London. — The Lewisham Borough Council has accepted the tender of ^Slr. J. Pearce for the supply 
of Portland cement in connection with laying concrete foundations in Sydenham Road, at 90s. 6d. per 
ton. The Cement Marketing Co., Ltd., quoted the same price. 

London. — The Stepney Borough Council has accepted the tender of INIessrs. D. T. Jackson for the 
construction of concrete foundations for a turbo-alternator at the Limehouse Electricity Generating 
Station, for the sum of £2,877 12s. 4^. 

Ludlow. — The Ludlow Rural District Council has accepted the tender of Messrs. Davies & Son, 
of Ludlow, for laying a concrete pavement at Craven Arms at iis. 3d. per yard super. 

Norwich. — The Norwich Town Council has accepted the tender of Messrs. Constable, Hart & 
Co., of London, for 5,000 superficial yards of concrete for street works, at 14s. per yard. 

Taunton. — ^The Taunton Town Council has provisionally accepted the tender of Messrs. Cowlin 
& Son, of Bristol, for the erection of a ferro-concrete bridge over the River Tone (from the designs of 
Messrs. Mouchel & Partners), at £12,192. 

208 ♦ 



I&^^^g^l^^ MEM OR A NBA . 

TENDERS INVITED. 

Grays. — March 12. The Grays Thurrock & Bilbury Joint Sewerage Board invite tenders for the 
construction of 1,060 yards of concrete sewer tube, and other sewerage work. Forms of tender, etc., 
from Mr. Midgley Taylor, Engineer, 36, Victoria Street, Westminster, S.W.i. 

Halifa.x. — Marcli 12. The Hahfax Corporation invites tenders for concreting and other work 
in connection with the foundations of two cooHng towers at the electricity works. Plans, etc., from 
Mr. James Lord, Borough Engineer, Crossley Street, Halifax. Deposit, £2 2S. 

Hemel Hempstead. — March 12. For the erection of eight cottages, for King's Langley Urban 
District Council. Mr. T. H. Lighbcdy, Architect, 20, Marlowes, Hemel Hempstead. Deposit, £1 is. 

HiNDERWELL. — March 12. For erection of 36 houses, for Hinderwell Urban District Council. 
Plans, etc., from Messrs. French and W'ilkins, Architects, Flowergate, Whitby. 

Brentford. — March 15. The Brentford Urban District Council invites tenders for the erection 
of 70 houses. Plans, etc., from Mr. W. J. W. Westlake, Borough Engineer and Surveyor, Clifden 
House, Boston Road, Brentford. 

Southampton'. — March 17. The Southampton Corporation invites tenders for the erection of 
100 houses. Plans, etc., froni the Borough Engineer, 123, High Street, Southampton. 

Stockton-on-Tees. — March 17. For erection of 226 houses for Stockton-on-Tees Corporation. 
Plans, etc., from Housing Architect, 90, High Street, Stockton-on Tees. Deposit, £3 3s. 

South Africa. — May 21. Tenders are invited by the Government of South Africa for the con- 
struction of one grain elevator (30,000 tons capacity), at Cape Town; one elevator (42,000 tons capacity), 
at Durban ; and thirty-four smaller grain elevators in various districts, in connection with the South 
African Railways and Harbours. Full particulars from the High Commissioner for the Union of South 
Africa, 32, \'ictoria Street, London, S.W.i. 

Bombay. — May 31. — The Corporation of Bombay invites tenders for the construction of about 103 
miles of steel and reinforced concrete pipe lines, and contingent works. Forms of tender, etc., may be 
obtained from Messrs. Taylor & Sons, Consulting Engineers, 36, Victoria Street, Westminster, S.W.i. 

PUBLICATIONS AND CATALOGUES RECEIVED. 

B. S. P. Pocket Book. — This handy Httle pocket book, pubHshed b}^ the British 
Steel Pihng Co., contains a great deal of useful information for the engineer and 
contractor regarding steel sheet piling. In addition metric tables are given, and 
some notes and diagrams for the calculation of water pressure and bending 
moments on piling, and calculations for wallings and struts. A section is devoted 
to pile driving and particulars and illustrations are given regarding the plant suppUed 
by this firm, which includes friction winches, pile hammers, pile shoes, concrete 
mixers, etc. Copies of this Pocket Book can be obtained from the British Steel 
Piling Company, Dock House, Billiter Street, E.C. 

NEW COMPANIES REGISTERED. 

Centrifugal Concrete Construction Syndicate, Ltd. (172,043). Registered December if>, 
1920 ; 28, Cockspur Street, S.\\'. Manufacturers of pipes, bricks, tiles, pottery, concrete, and artificial 
stone. Nominal capital, £10,500 in 10,000 £1 shares, and 10,000 is. shares. Directors to be appointed 
by subscribers ; remuneration to be voted. 

E. H. White & Co., Ltd. (172,283). Registered December 28, 1920. The Arches, Longwood, 
Huddersfield. Concrete and Concrete ]31ock Manufacturers. Nominal capital, £2,000, in 2,000 £1 
shares. Directors : W. H. Robinson, New Street, Mihisbridge, Huddersfield ; W. E. Schofield, Thorn- 
field, Milnsbridge ; and H. W. Schofield, 14, Western Road, Cowlersley, Mihisbridge. Qualification 
of Directors, £50 ; remuneration to be voted. 

Constone, Ltd. (172,515). Registered January 10. Manufacturers of artificial stone, reinforced 
concrete, etc. Nominal capital, £10,000 in 10,000 £1 shares. Directors: D. Cappella, 5, Evington 
Valley Road, Leicester; G. H. Cherry, 17, Bannerman Road, Leicester; W. Foulds, 422, Marl- 
borough Road, Leicester ; V. H. Jones, 340, Victoria Park Road, Leicester ; F. Murby, 54, Nuffield 
Road, Leicester ; and J. H. Wakefield, Huncote Road, Marlborough. Qualification of Directors, 500 
shares ; remuneration to be voted. 

National Fireprooiing Co., Ltd. (172,466). Registered January 6. Manufacturers of plaster 
slab machines. Nominal capital, £100,000 in 100,000 £1 shares. Directors : W. Collier, 60, Leigh 
Road, Leigh ; J. Fogg, Alpine House, Pennington, Leigh ; V. ]\L Johnson, "The Cottage," Beacon 
Hill, Newark; J. Livesey, 30, Swinley Road, \\'igan ; A. "S'oung, Kilncy Court, Worthington, near 
Wigan. Qualification of Directors, £2,500 ; remuneration £100 each (Chairman, £125). 

South of England Concrete Moulding Co., Ltd. (172,676). Registered January 24. Cement 
slab manufacturers. Nominal capital, £8,500 in 8,500 £1 shares. Directors : W. H. Wroth, Horse- 
bridge F'arm, Kingsomborne, Hants ; P. E. S. Parker, lOakleigh, Lakewood Road, Chandler's Ford, 
Hants; and J. T. Matthews, St. Michel's Chambers, Southampton. Qualification of Directors, £100 ; 
remuneration, £50 each (CJiairnian £100). 

Bloxham and Sci;fi-ells, Ltd. (172,902). 70A, Basinghall Street, E.C. 3. Registered February 
I. Steel and ferro-concrete cc^nstructors and builders. Nominal capital, £2,500 in 1,000 £1 preference 
shares, 1,484 £1 ordinary shares, and 16 £1 founders' shares. Directors: C. A. Bloxham, C. C. Baker, 
and R. O. Grant. Qualification of Directors, £100 ; remuneration, £50. 

Stronghold Cement Block Construction and Machink Co., Ltd. (172,941). 34-35, Norfolk 
Street, Strand, W.C.2. Registered l-'ebruary 2. To acquire patents and inventions for improved 
methods of erecting iiortabic concrete buildings, and to manufacture cement blocks, etc. Nominal 
capital, £10, 000 in 20 £20 picfercncc sliares, 8i)<; £10 ordinary shares, and 10 £1 ordinary shares. Direc- 
tors: A. Lusty, P. A. Smith, and E. J. Ward. Qualification of Directors, 10 shares; remuneration 
to be voted by Company. 

209 



MEMORANDA. 



[CQNCBETEI 



RECENT PATENT APPLICATIONS. 



112 
143 

154 
154 

it54 
154 

154 

154 
154 
154 

154 
154 
154, 

154 

154 

154 



,449.- — W. C. Davis : Reinforced concrete 

walls. 
,270 and 132,272. — Steven's Partition and 

I'loor Deadener Co. : Floor construction. 
,209. — Bonnett et Fils : Moulds for concrete 

blocks. 

,229. — H. E. Brown : Concrete wall con- 
struction. 
,547. — ^T. Moser : Method of spraying 

mortar or concrete. 

gQi. — \v. Marriott: Concrete reinforce- 
ment. 
051. — N. A. M. McDowell: Concrete 

block-making machine. 

,090. — A. M. Cramer : Hollow building 
blocks. 

ogi. — J. D. Roots : Slab wall construction. 
096. — Concrete Dwellings, Ltd., and H. 

Eldon- Brown : Pre-cast concrete moulds. 
236. — K. Friedrich : Glazing cement and 

other building materials. 

327. — R. Lowry : Concrete cavity walls. 

37g. — F. Walker : Building blocks. 

3Q2. — M. M. Smith : Wall construction 

461. — G. H. Forrester : Concrete walls. 

^84. — W. Muirhead : Concrete shoes for piles. 

510, — F. W. Bakema : Furnaces for 

cement manufacture. 

520. — P. C. Cannon : Moulds for concrete 

blocks, pipes, posts, etc. 

759.— T. A. & J. L. G. Aldridge : Building 

blocks and slabs. 

7S0. — C. E. Masters : Manufacture of 

building blocks. 



E. Gerard & L. G. Mouchel & 
: Reinforced concrete construction. 
E. Clifton & J. S. Ewart : Concrete 



154,811. — H. D. «S: C. H. Henderson: Moulds 

for making concrete blocks. 
155,043- — A. E. Marshall: Concrete floors. 
155,072. — C. McDowall : Fireproof floors. 
155,075. — R. C. Little Johns : Concrete block 

mould. 
155,120. — J. Thewlis: Cavity concrete walls. 
155,127. — J. Ryan: Method of fixing building 

blocks. 
155.326.— H. 

Partners 
i55,3B5.— W. 

floors and roofs. 
155,431. — H. D. Baylor : Manufacture of slow- 
setting, fat and waterproof cement. 
155,454- — !■"- Malgarini : Reinforced hollow blocks. 
155,599. — C. Rabut : Means of camping 

together component wall parts. 
156,819. — G. H. Forrester, G. Marsh and J. D. 

Marsh : Concrete building construction. 
156,882. — F. A. Noullett : Building blocks. 
156,933. — J. R. Matthew and G. R. Bowers: 

Concrete slab or block buildings. 
156,934. — R. E. Matthews and J. R. Bowers : 

Method of erecting concrete-slab or block 

buildings. 
156,973. — F. C. C. Rings : Reinforced concrete 

floors 
156,275. — J. Claughton : Concrete houses. 
156,319. — D. de Nagy : Building blocks. 
156,385. — W. Turner : Concrete sewers and 

tubes. 
156,442. — H. J. C. Forrester : Insulating building 

material. 



CONCRETE 



CHIMNEY SHAFTS 



Important 

Contracts 

now in 

Progress. 



on the 

"MONNOYER" 

SYSTEM. 



Boiler 

and 

Economiser 

Settings. 



Sole Concessionaries for the United Kingdom, 



Telephone : Victoria 4700. 

CHIMNEYS LD. 



Telegrams : Stablochim, Vic, London. 
Head Office : 

47 Victoria Street, London, S.W.I. 



Glasgow : 38 Oswald Street. South Wales : 1 Western Mail BuUdings, Cardiff. 

Manchester : Barton House, 66 Decuisgate. 



CONCRETE 

AND 

CONSTRUCTIONAL ENGrNEERING 



Volume XVI. No. 4. London", April, 1921. 

EDITORIAL NOTES. 

AMERICAN METHODS, 

INTRODUCTION. 

The execution of concrete work in all countries where modern methods are known 
must necessarily follow on similar Hues, but the cost, speed and quality of the 
work may be considerably affected by the manner in which the methods are 
applied, and for this reason some benefit may be obtained by a comparison between 
the general principles which govern the execution in any two countries. 

Mass production has always been a strong feature in American industry, and 
a study of the methods employed in the building trade, and in concrete work in 
particular, reveals the fact that the Americans have a natural aptitude for organis- 
ing and executing large schemes in the minimum possible time. We do not wish 
to imply that this natural aptitude is confined to the Americans alone, but it is 
certainly more in evidence ; and this fact may be due to the industrial develop- 
ments which provide more opportunity to the engineer and contractor, but 
certainly full advantage is taken of such opportunity. Generally speaking, 
however, in this country there is a strong conservative tendency and development 
is hampered instead of being encouraged by those who could do much in the 
cause of progression. An illustration of this can be found by a comparison of 
the research work carried out in the United States and this country in connection 
with all classes of concrete work, and again in the adoption of the mushroom 
or flat slab system in the former country and its prohibition here. 

In connection with speed there is a general impression that everything is 
quick in the United States, but a careful analysis will indicate that this impression 
is incorrect, as in many respects the speed does not exist, and there is a curious 
inconsistency between the wonderful speed that is achieved in large projects 
where pressure is applied and the many ordinary services in the daily routine 
where no pressure is applied and things are extremely slow. Many instances 
could be given to illustrate this statement, but they do not come within the 
scope of these notes, and the inconsistency is mentioned merely to show the 
■effect of efficient organisation and its application to building work. 

ORGANISATION. 

Considerable time and thought are expended on the question of organisation 
in American contracts, and the whole scheme is laid out before anj' work is 
commenced. Generally speaking, the American contractor appears to be slow 
in making a commencement of the work on the site itself, but in reality ho is 



AMERICAN METHODS. [CQNCTETE] 

busy planning and deciding on the chief features of the plant lay-out, the flow of 
materials and the main points to be considered before any actual work of erection 
is started, and in this respect time and money are saved when the work is in hand. 

Various sketch plans are prepared to give alternative schemes for the location 
of concrete mixers, industrial and standard gauge tracks, storage yards, shops and 
mills generally, and the sequence of execution is carefully considered. These 
sketch plans are then discussed from various standpoints, and a final plan is 
prepared which provides a definite location for all stationary equipment, stores 
and temporary offices, together with the track runs that will be necessary, 
temporary water and power lines, and all the items required during the construc- 
tion period. 

The arrangements, being carefully determined by a good organiser in the 
first instance, are only varied to suit any exceptional circumstances that may arise 
during the course of the work, and a definite method of this nature enables the 
construction to be carried out uninterruptedly with the minimum of labour and 
cost. 

The same principle is followed, of course, by many large contractors in this 
country, but not in such a thorough manner, and continual re-arrangements and 
modifications are often necessary, owing to the casual consideration given to- 
extremely important points in the first instance. 

In concrete work the initial lay-out is probably more important than in any 
other trade, because the sequence of operations must be planned to avoid passing 
over work newly executed, and the flow of the raw materials to the point of 
mixing and the methods of handling the mixed concrete will have considerable 
effect on the cost of the work. 

THE USE OF PLANT. 

The most striking feature of American concrete work is the extensive use of 
plant of every description, and it is this factor which is mainly responsible for 
the speed so often achieved. Every machine which can profitably be employed 
is provided as a matter of course, and a bold policy is pursued in providing equip- 
ment on a large scale, which reduces labour to a minimum and increases output to 
the maximum. On work of any magnitude one or more stationar}^ concreting 
plants are installed with derrick, hoppers for storage, hoisting towers, chutes and 
elevators complete, and the output from a well-designed plant is considerable. 
A convenient point is selected for the installation and, if possible, a standard 
gauge track is carried right up to the plant to facilitate the unloading of raw 
materials. Cement storage sheds are built adjoining the track to allow this 
material to be unloaded and handled directly into the shed, and sloping run- 
ways or belt conveyers are provided to give a direct supply of cement to the 
gauging hopper over the concrete mixer. Immediately over the mixer large 
ijins constructed of heavy timbers are erected for the storage of fine or coarse 
aggregate with hopper bottoms discharging directly into the gauging hopper 
of the mixer. A derrick is installed adjacent to the tracks, and by means of a 
grab bucket the aggregate is unloaded from the railwaj^ cars directly into the 
storage bins in a quick and economical manner. 

The discharge from the mixer— (usually of the maximum capacity) — is made 
directly into a bucket elevator which raises the mixed concrete to the desired 



U, CONSTRUCTIONAL 
^ ENGTNF.y P INC, — : 



AMERICAN METHODS. 



height on the tower where it is tripped to discharge into the chutes and thus 
flow by gravity to the point required. With a weh-designed plant of this kind, 
the output is frequently as much as one cubic yard per minute, which means 
480 yards cube in a working day of eight hours. Objection to spouting concrete 
by means of towers and chutes has been raised by many engineers in this country 
owing to the separation of the coarse aggregate during the gravity flow, but in 
all important work the mixed concrete is not spouted directly into position, but is 
discharged into a large receiving hopper where the whole of the material comes 
together again, and from this hopper it is measured out into light concrete buggies 
and transported by hand to the point where it is actually placed. The buggies 
are light metal receivers carried on two wheels which are easily handled and 
much preferable to the ordinary type of wheelbarrow so often employed. In 
transporting the concrete care is exercised to provide light runways which permit 
of a continuous flow of buggy pushers from the hopper to the place of deposit in 
such a manner that a complete circuit is made and no time is lost by waiting. 
It is a common sight in many concreting operations to see a line of men held up 
at some point owing to the necessity of allowing a string of returning empties to 
cross a narrow gangway to reach the loading point, with a consequent cessation 
of work both at the place of deposit and the point of loading. When a central 
concreting plant is required to mix material for some work too far removed to 
allow of spouting and hand wheeling, the mixture is discharged into a suitable 
hopper at any convenient spot for the purpose of feeding into special hopper 
cars which are transported over ordinary narrow-gauge track to the required 
situation. These cars have hopper gates which open to discharge the concrete 
at the side, either into wooden chutes or buggies, according to circumstances. 
These trains are commonly called " soup trains " in America, and some very 
quick work can be accomplished by their use. In some cases when towers are 
not apphcable a standard-gauge track is laid alongside the work and a train is 
made up consisting of cars of aggregate and cement attached to a flat-bottomed 
car, on which a concrete mixer with petrol-driven engine is attached, and this 
can operate up and down the length of the work as required, while additional 
supplies of raw materials can be brought to the mixer with the minimum amount 
of handling. 

By these and similar methods concrete work is being economically and 
quickly executed in America, and a very progressive spirit is shown by the manner 
in w^iich the fullest advantage is taken of any equipment suitable for the work 
in hand. The same spirit is shown in all the other work in the building industry, 
as extensive use is made of steam-shovels, trench-diggers, ploughs, scrapers, 
derricks, compressed-air plants, locomotive cranes and hoisting appliances of 
all kinds. 

A conscientious study of many of the appliances used in America by the 
engineers and contractors of this country would lead to a more extensive adoption 
here with a consequent saving in time and money, more especiafly on schemes of 
any magnitude. 

FORMWORK. 

Every advantage appears to be taken of standardisation of forms, and 
wherever possible sections easily erected and dismantled for re-use are employed 
to reduce the carpenter's work on the actual structure to the minimum. 

213 



AMERICAN METHODS. [CDNCBETE] 

Timber is plentiful and there is, in consequence, a natural tendency to 
extravagance in the use and waste of this material, but, as a general rule, the 
American carpenter is ver}'' expert in the speedy erection of plain carpentry 
work of the kind required in the forms for concreting. 

Extensive use is made of concrete distance pieces and universal clamps, 
which facilitate easy removal, and a well-designed form is usually adopted. In 
the case of the " flat slab " type of building which is so extensively used steel 
forms are always used for the interior columns and their caps, and these can be 
hired on terms which are advantageous as compared with the cost of making 
special forms for any one scheme. 

REINFORCEMENT. 

\\Tierever possible advantage is taken of reinforcement made up previous 
to placing in position and the rods are wired together to ensure easy handling, 
while plain and deformed bars are used impartially. , 

Careful supervision is invariably required in the placing of the steel, and also 
to see that it is not displaced during the concreting operations, as there appears 
to be a general tendency to carelessness both in the workmen and foreman which 
is aggravated by the speed usually maintained. Inserts for the attachment of 
pipe-hangers and other fittings are extensively used, these being placed on the 
formwork and kept in position by nailing to prevent displacement during concret- 
ing, these inserts being obtainable in many different types and ensuring easy 
and satisfactory attachment. 

In American practice there is a marked tendency to use small diameter rods 
in large numbers in preference to fewer and larger rods, but in many instances 
this appears to be carried to excess, thus making the reinforcement unnecessarily 
complicated and difficult in execution. 

CONCLUSION. 

The speed which is maintained renders it necessary to provide several methods 
of protecting the work already executed, and as the floors on a building are often 
finished by treating the surface of the structural concrete immediately with neat 
cement and floating to give a finished surface on which it is necessary for workmen 
to work at the earliest moment, extensive use is made of sawdust with very 
good results. 

In many cases black labour is employed on concrete work, and satisfactory 
work is obtained if good supervision is provided, while the organising of the 
scheme to produce competition between different gangs is a big factor in the 
speed. 

Generally, a study of American methods of executing concrete discloses 
two main factors as contributing to quick and economical work, viz., good organisa- 
tion and the extensive use of plant and equipment of all kinds. The quality is 
fairly well maintained as a general rule, and we feel that it would be of advantage 
to the industry in this country if more use was made of several good ideas which 
are so frequently applied in America. 



214 



r ?, CONSTCUCnONAlJ 
[6^ FMr.n;!?.)F :RING ^J 



REINFORCED CONCRETE REFUSE STAITH. 









REINFORCED CONCRETE 
REFUSE STAITH. 

CONSTRUCTED FOR THE GATESHEAD CORPORATION. 

In common with all the great seaports, and many smaller ports and harbours 
of the British Isles, Newcastle-on-Tyne, Gateshead and other towns in the district 
known as Tyneside possess numerous examples of reinforced-concrete construc- 
tion, some dating back twenty years or more, and others recently completed or 
in course of execution. 

One of the latest reinforced-concrete works commenced on the Tyne is the 
staith, or wharf, described below. The method of dealing with town refuse 
for which the staith was built, had previously been adopted by the City of London 
Corporation, for whom a reinforced-concrete jetty was built on the Thames in 
1905. Although employed for a similar purpose, the jetty does not embody 
the more recent and ingenious structural and mechanical devices for the con- 
venient handling of refuse which form part of the Gateshead staith. 

In the year 191 1 the Corporation of Gateshead on the recommendation of 
the Borough Engineer, Mr. N. Percy Pattinson, decided upon the construction 
of a staith and overhead gantry for the disposal of^town refuse by loading it 
into barges or lighters, such vessels being afterwards towed down the River 
Tyne and discharged in the North Sea. 

The site chosen for the erection of the new staith is on the south bank of 
the river near the North-Eastern Railway Goods Depot and Locomotive Works 
immediately above the renowned High Level Bridge of Robert Stephenson. 

In pursuance of their project, the Corporation in the year stated issued invita- 
tions to four firms of structural engineers to submit designs, specifications and 
accompanying estimates of cost. These were received in due course and early 
in the year 1912 were submitted by the Corporation to Messrs. D. Balfour & Son, 
civil engineers of Newcastle-on-Tyne and London, for investigation and advice 
as to the relative merits of the four schemes put forward. 

Having gone fully into the drawings, checked the stresses involved and con- 
sidered the provisions made for resistance to the latter, Messrs. Balfour & Son 
came to the conclusion that the scheme prepared by Messrs. L. G. Mouchel & 
Partners, Limited, of Westminster and Newcastle-on-Tyne, was calculated most 
efficiently and economically to comply with the requirements of the case. 

Consequently this scheme, embodying the application of Mouchel-Hennebique 
reinforced-concrete construction, was recommended to and subsequently adopted 
by the Corporation of Gateshead. 

Before the proposed work could be taken in hand, it was necessary to obtain 



J15 



REINFORCED CONCRETE REFUSE STAITH 



ICQNCBETE] 




Fig. lA. 



Reinforced Concrete JRefuse SxArrH. Gateshead. 



2l6 



L&^^^N^:^ REINFORCED CONCRETE REFUSE STAITH. 

the sanction of the Local Government Board as a preliminary to the issue of a 
loan in respect of the cost of construction. Fully detailed working drawings, 
together with the calculated moments and stresses were then prepared and sub- 
mitted to the Local Government Board, by whom a local inquiry was held in 
1914, when the scheme was fully gone into and explained by Messrs. D. Balfour 
& Son, the civil engineers acting on behalf of the Corporation. 

After receiving the report of their Engineering Inspector, the Board sanc- 
tioned the scheme and granted a loan repayable in twenty-two years. Although 
this sanction was given in 1914, the outbreak of war was responsible for the 
deferring of construction until last year, when a start was made by the contrac- 
tors, Messrs. Brims & Co., of Newcastle-on-Tyne and London. The resident 
Engineer was Mr. R. G. Huck, of Heaton. 

Figs. I and la include longitudinal and cross sections of the staith and 
overhead gantry in accordance with the complete project, only part of which is 
now being carried into execution. 

Commencing at the river end, the staith projects 36 ft. beyond the bank and 
is 38 ft. in width. This portion is founded on reinforced-concrete piles and 
cylinder piers, strongly braced and covered by decking which extends back 76 ft. 
from the river front, the back part of the decking being supported by reinforced- 
concrete piles and rectangular piers founded on similar piles. The staith and 
the foundation behind it carry the river end of the gantry, which includes a 
range of four triangular bunkers, each 33 ft. high by 36 ft. from front to back 
at the top by 8 ft. wide inside, as well as tipping platforms and the necessary 
mechanical equipment for the delivery of refuse into light craft. 

Refuse will be brought to the bunkers along a gallery 357 ft. in length by 
37 ft. in width inside, the landward end of the gallery starting from the top of 
the river bank which is 78 ft. above the level of the ground along the river front. 
The gallery is 12 ft. high from floor to flat roofing, the latter being supported 
by columns spaced 6 ft. apart, centre to centre. The triangular framed structure 
carrying the refuse bunkers and the river end of the upper gallery, is formed 
of columns and horizontal bracing members, the rigidity of the connections 
being aided by knee braces of ample proportions. The construction at the 
extreme end enclosing the refuse shoots is of similar character. 

The landward end of the main triangular framework includes a pair of rect- 
angular piers, 99 ft. in height from base to top and tapering from 6 ft. 3 in. to 
3 ft. m diameter. These piers are founded on reinforced-concrete piles which 
project into the interior of the pier at the lower end. The piers thus firmly 
rooted into the ground form a solid and substantial abutment for the bridge 
shown in the drawing, at the same time affording vertical support for the inner 
face of the triangular frame. 

The piers are braced together near the bottom by members entering into the 
construction of the staith decking, at the top by the transverse floor and roof 
beams, and at four intermediate levels by special bracings as shown. 

The framework contributed very effectively to the lateral rigidity of the 
superstructure, which, owing to its great height, obviously needs most adequate 
wmd bracing, especially during the easterly gales sweeping up the vallev of 
the Tyne in the equinoxes. 

Along the lower bank of the river runs a roadway, across which passes tlie 



217 



REINFORCED CONCRETE REFUSE ST AIT H. 



iCDNCKETEJ 



upper gallery, constituting a bridge with two 50 ft. continuous girder spans. 
The landward abutment is provided by a pair of tapering piers 84 ft. in total 
height and a third pair of piers, 91 ft. high, form an intermediate support. These 
piers strongly braced transversely are of generally similar construction to that 
of the pair first described, save in the respects that they arc built up from extended 
footings instead of being founded upon piles, and that the landward abutment 
has the spaces filled in with a vertical slab of ferro-concrete with stiffening ribs, 
the whole in monolithic connection, and converting the abutment into a retaining 




LONGITUDINAL SECTION 




PLAN OF LOWER WHARF 

Fig. 2. 
Reinforced Concrete Refuse Staith, Gateshead. 



wall capable of holding up any filling material deposited behind it, while at the 
same time the vertical slab acts as an end wall to the two lower storeys of 
galleries at the landward end of the gantry. 

The lower galleries, divided up into chambers of various sizes as represented 
in Fig. I, are 204 ft. and 154 ft. long respectively, one starting 12 ft. from the 
top edge of the river bank and the other commencing at a distance of 61 ft. from 
the same line. They will be utilised as stables, cartsheds and garage for motor 
wagons belonging to the Corporation. The construction is very much like 
that of the topmost gallery and the three storeys are supported bv seven pairs 

218 



a, CONSTCUCnCSMAL 
A ENGTNEEJilNG — ; 



REINFORCED CONCRETE REFUSE STAITH. 



of columns and four pairs of tapering piers, all rising from extended footings. 
Access will be given to the various galleries by means of inclined gangways. 

Let us now turn to the structural details of the new staith, the first section 
of the work represented in its finally complete form by Fig. 2. 

Briefly described the staith comprises a reinforced-concrete platform, 75 ft. 
from front to back by T)^ ft. wide carried on fifty-three Hennebique reinforced- 
concrete piles, 16 in. square in cross section driven for the most part in pairs 
to an average depth of 24 ft. below water level, and providing for the river bed 
immediately in front to be dredged to a depth of 12 ft. below L.W.O.S.T. 

Fig. 2 includes a longitudinal section and a plan of the staith below the deck- 
ing. Each pair of piles in the front row is enclosed by a reinforced-concrete 




Fig. 3. Details of Typical Main Beam. 
Reinforced Co><crete Refise Staith, Gateshe.\d. 



cylinder, 4 ft. 6 in. in diameter, the shell being made of precast sections 4 in. 
in thickness. After the sections have been lowered into position one after 
another until the pier has been built up to the predetermined height, they are 
jointed together with cement grout and the interior is filled in with concrete 
suitably reinforced so as to form a solid pier. 

Piers of the type in question are of much value along the front of a wharf 
or jetty because of their great strength and rigidity, and can therefore be spaced 
far wider apart than reinforced-concrete or other piles. Moreover, they can be. 
and in many instances have been employed without bracing members inter- 
mediate between the bed of the sea or river and the beams connecting the piers 



C2 



219 



REINFORCED CONCRETE REFUSE STAITH. 



iCQNCPETFJ 




.lf«^^4l« 




Jm. 4. .-Mi'iwing Cylinders. 



Fifj. 5. Mi'.'.Mii;; J. .111(1 I'liw Mnpiied for Heain 
and Decking Connections. 




Fig. 6. Showing Beam Steel in Position. 




Fig. 7. Showing Decking. 
Reinforced Conxrete Refuse St.mth, Gateshead. 



r 9- COT>f5TBUCn<XAl3 
jti ENGTNE^RING ^ 



REINFORCED CONCRETE REFUSE STAITH. 





Fig. 5. hhuwiug iixcii Steelwork above 
ground level in Column A. 



Fig. 9. Pitching Pile. 




Fig. 10. Showing Pitching of Pile. Fig. 11. Showing Pitching ot I'lle. 

Reinforced Concrete Refuse Staith, Gateshead. 



221 



REINFORCED CONCRETE REFUSE STAITH. [CDNCTETE ] 



at top. Thus this type of pier obviates the difficulty in the way of bracing 
ordinary piles in subaqueous work. 

One of the first things done by Messrs. Brims & Co. in commencing opera- 
tions was to establish a yard near the site of the staith for moulding and seasoning 
piles and cyhnder sections. The cylinder sections are 13 ft. long each by 4 ft. 
6 in. in diameter. The piles were slung by the aid of a derrick crane to the 
positions where they were driven, as illustrated by Figs. 9,10,11. Measuring 
48 ft. in length by 16 in. square and weighing about 5 tons each, the piles were 
slung and pitched as shown by the illustrations, in the second of which one of 
the piles may be seen close to the pile-driving machine. 

When the piles had been driven to refusal, they were trimmed off to uniform 
level at the top and the concrete was stripped away so as to allow the reinforcing 
bars to be incorporated with the caps formed for connection with the bracing 
members below high water level, those in the front row being enclosed by the 
cylinder sections. The two front rows of piles on the landward side were incor- 
porated with the beams of the decking, and those in the back row of all were 
incorporated in the columns to be extended later to the top of the overhead 
gantry. It may here be said that the piers, piles and columns have been designed 
of sufficient strength to carry the lofty superstructure to be erected hereafter, 
and that special provision has been made at the head of each column for the 
satisfactory connection of the new and old work. 

Fig. 3 gives details of a typical main beam, and part of the provision made 
for carrying the platforms to be employed in tipping refuse into vessels alongside 
the new staith. 



BRIDGE OVER THE MACQUARIE RIVER, 
NEW SOUTH WALES. 

After a life of fifty years the timber bridge over Macquarie River, New South 
Wales, has been replaced by the structure illustrated in oiu" Frontispiece. 

The structure consists of two steel truss spans each of 120 ft. centres of bear- 
ings and eleven reinforced concrete approach spans on reinforced concrete piers 
and abutments. The roadway for vehicular traffic is 20 ft. between kerbs and 
is of reinforced concrete with a cantilever footway 5 ft. wide. 

The piers consist of two reinforced concrete shafts braced at intervals by 
webs about 10 ft. deep by 18 in. thick for the main piers and 12 in. for the piers under 
the approach spans. The shafts are octagonal in section, of varying dimensions 
and are stepped from top to bottom to square bases which are supported by timber 
piles driven into the bed* of the river. 

The shaft of the centre pier under the two steel spans is 5 ft. by 5 ft. 
outside increasing to 6 ft. by 6 ft. just above the base, which is 10 ft. by 15 ft. 
by 5 ft. thick, the two bases being connected with a web 2 ft. 6 in. wide the full 
depth of the footings. The specification provided for the concrete being laid in 
the dry, and steel sheet piling was driven 20 ft. into the gravel of the river bed. 
The pumps could however only lower the level of the water one foot and eventually 
the bottom was sealed by depositing concrete 2 ft. thick over the bottom of the 
excavation and building a timber coffer-dam inside the steel piling. This allowed 
the remainder of the work being completed in the dry. 

(Continued on page 265.) 



c^ 



PORTLAND CEMENT. 




PORTLAND CEMENT. 

ITS TESTING AND SPECI- 
FICATION—BRITISH AND 
FOREIGN METHODS. 



By R. E. STRADLING, M.C., B.Sc, A.M.I.C.E., A.M. Am.Soc.C.E. (Lecturer in 

Civil Engineering University of Birmingham). 

The first pari of this article appeared in our March Number, page ifg— Ed. 



TABLE VII. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 



"British. 
U.S.A. 
French. 
German, 



Not used. 
Not used. 
Not used. 
Not used. 



Strength Tests [contd.). 
Compression Tests. {Neat Cement.) 



D. Compression Tests. 



{Cement and Sand.) 
"British. Not used. 
U.S.A. Not used. 
French. Not used. 
German, i to 3 standard quartz sand. All sand is tested by Royal Institute of Testmg 

Materials, and supplied through the Cement Manufacturers' Laboratory, Kar- 

shorst, in sealed bags. Passes 1-35 mm. (-0533") mesh and retained on -775 mm. 

(0'0 30 5) mesh. 

850-860 gms. of mortar filled in cube moulds (50 sq. cm. side) by Boehme hammer 

(150 blows) 24 hrs. in moist air. 

After 7 days old at least 120 kilo/cm^ [€^ 1720 Ib/D") 
„ 28 ,, „ „ ,, 250 „ ,, (=2: 3570 Ib/D") 

The points to be noted about the German specifications for this test are : — 
(i) Standard sand prepared at one place and tested there ; then sold in sealed 
packets. 

(2) Mechanical mixing. 

(3) Mechanical ramming. 

This test appears to the writer to be as free from the personal equation as it is 
possible at present to make it. 

With regard to compression tests in general ; the real troubles with them are : — 
(i) Difficulty of getting central loading. 

(2) Variation of strength with the kind of material through which the load is 
applied to the specimen (e.g. lead sheet, steel, felt). 

(3) Difficulty of knowing wliat kind of stress is actually being measured. 
7^^/^. 14 shows fracture of cement blocks. 

It will be seen the cube has fractured along what are roughly diagonal planes. 
There are two possible explanations of this : — 
(i) Shear failure (maximum shear planes). 
(2) Tension failure at right angles to direction of loading. 

If the former is the cause of failure, fairly consistent results might be expected. 
If tlic latter, every difference in the surfaces (cement block and plate of testing 

223 



R. E. STRADLING. [CONCRETEJ 



machine) will cause this to vary, as the strength is probably a function of the 
coefficient of friction between them as well as other variables. 

It appears to the writer that the most suitable test for ordinary work is the 
tensile test— cement and sand. 

The factors affecting the strength are shown in Figs. 15 to 19. 

*Fig. 15. Variation with water content. 

*Fig. 16. Time of mixing. 

*Fig. 17. Temperature of materials. 

^Fig. 18. History of Specimen. 

^Fig. 19. History of Specimen. 

These curves show the great importance of : — 

(i) Fixing the proportion of water to be used. 

(2) Keeping conditions of mixing content. 

(3) Keeping conditions of storage content. 

The chief difficult}^ is, of course, the first — the amount of water. The British 
specification makes'but little attempt to help in this subject. 




Fig. 14. 



France and U.S.A. do specify, as has been seen, the methods of obtaining a 
consistent proportion of water. 

Germany has the most elaborate method and I suggest probably the most accurate. 

Setting Time. 

As stated at the beginning of this paper the setting of a cement is a chemical % 

action taking place over a short or long period according to the sample of cement. 
When any chemical action takes place, some thermal change practically always 
accompanies it. 

Taking advantage of this fact, the progress of chemical action in a setting cement 
can be watched by means of registering temperature changes. A sqries of experiments 
in this was carried out by M. Gary and I reproduce three of his diagrams in Figs. 20, 
21, and 23. J 

Under suitable conditions these thermal methods give a far better guide to the 

* Plotted from data of Steinbruck, given in Desch-Chemistry and Testing of Cement. 

t From Faber and Bowie, R.C. Design, Vol. i. 

X From Concrete and Constructional Engineering, 1901-1907, Vol. i, pp; 356, 432-3. 

224 



&CONSTDOCTlOT>fAL 
EMGINE£B1NG — , 



PORTLAND CEMENT. 



" setting time " than the arbitrary mechanical tests of the " Vicat Needle." 

In Figs. 20 and 21 the Initial and Final sets as registered bj^ the Vicat needle are 

marked I and F respectively. It will be seen that the chemical action causing a rise 

in temperature is starting before the initial set as registered by the Vicat needle method. 

Again, although in Fig. 20 the Final set as registered by Thermal method and Vicat 









Fig. 15. 



1% OA-\S ©>-0 






"r\t>e C^'xi) 




op T<i/vreT=nA.i-s 

'^ R.oovv\. 



Fig. 17. 



'3'n=lrvftRUCK. (v^oi) 



-^ 






















^ 


2 


f\ 












> 


^ 


-^ 








\ 








^ 


^ 














5 / 




V 


^ 


y 


















S ' 


























1 




















































1 4mj la tir 


list 


)ays In « 


\ ' ' " " 1 


It <VS M 










~ 










' 



-Curve showing eflect of drjfing a spfnnien of concrrt^" prcviotily 
imm<T5P'' 

Fig. 18. 



/ 
























/ 
























1 ' 
/ 

1 ( 


I 






^ 


— 


























/ 

/ 


\j 


X 




































































/ 
























/ rf«/ moht 


I t s 


s « 


' • ' '• "i 




' 














' 



Cur«e ihowiog elT.ci of imnif r^lng t Bptcimeii o( conaen 
proviuusly drj . 

Fig. 19. 



needle are practically identical, in Fig. 2 1 the Final set registered by the \'icat needle 
occurs at about 10-9 hours after mixing, but the real temperature rise of magnitude in 
this cement occurred at about 18-3 hours after mixing. 

It would seem to be a dangerous proceeding to disturb this cement for some con- 
siderable time after mixing, if this comparatively violent chemical action is going on. 

In general tlie lowest point in the curve indicates approximately the initial set as 
registered by tlie Vicat needle and the highest point, the final set — though this latter 



R. E. STRADLING. 



[CONCRETEJ 



does not always correspond. As already stated in one case given the " peak " on the 
temperature curve occurred about eight hours after the final set as registered by the 
Vicat needle. This kind of thing might certainly be dangerous in practice. 

Table VIII. gives a comparison of the various methods used. 

As will be seen the Vicat needle is used in all cases. 







<1 I* IT ti tl M 



o. Prof. Gary's Cur\es ok Tempera- 
ture Rise as Setting of Cement. 




Fig. 21. .\s Fig. so, Another Sample. 

TABLE VIII. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 
Setting Time. 
"British. Vicat needle with special needle for final set. 

Initial — Not less than 20 minutes. Needle just fails to pierce whole block com- 
pletely. 
Final — Not more than 10 hours. Special needle point just marks, ring does not. 
If specially quick setting cement is required initial not less than 2 mins. final 
30 mins. 
U.S.A. Vicat or Gillmore needles. 

Vicat : Initial — Not less than 45 mins. Just sinks to within 5 mm. of bottom 
of pat in ^ min. 
Final — Fails to mark. To be within 10 hours. 
Gillmore : Initial — Not less than 60 mins. Pat J" thick x 3" diam. to bear 
without appreciable indentation a needle ^^l" diam. weighing J lb. 
Final — Within 10 hours : pat to bear needle J^j" diam. with i lb. load. 
*French. Vicat needle i sq. mm. in section. 

Initial— 'Not less than 20 mins. (needle does not wholly penetrate). 
Final — Min. 2 hrs. I . ■ •■ , j. x- 1 

Max 12 hrs )°°^ appreciable penetration, e.g. -jL mm. 

German. Vicat needle cylindrical i sq. mm. 

Initial not less than i hr. Final not required. 

• As shown values are for other than sea work. For sea work final setting is minimum 3 hours, 
maximum 12 hours. 

226 



CCWSTBUCnCTvWJLl 
EMGTNy y P ' NT. — J 



PORTLAND CEMENT. 



Manufacturer's arrangements 



During manufacture, the setting time of a cement is kept within the required 
limits by (i) the addition of gypsum; (2) treating with steam, or (3) combination of 
(i) and (2). 

We are deahng with it here as received from the makers' works. 

At this point the setting time of an actual sample is influenced by three variables : 

(i) Amount of water. 

(2) Temperature. 

(3) Aeration of cement. 

It must be realised that the tests for setting if properly carried out in a laboratory' 
do not give a measure of the setting time as realised in works. The laboratory time is 
almost always shorter. This is due chiefly to the extra water used in practice. 

In the case of certain cements where the setting time is controlled by gypsum only, 
prolonged storage on the site may produce the opposite effect (i.e. a much quicker set) 
which rasij more than counterbalance the retarding effect due to excess of water. 

Some of these effects are shown in Fig. 22. These curves are plotted from data 
obtained by Prof. R. K. Meade. 

These show variation of setting time with : — 

(i) Fineness of grinding ) 

(2) Gypsum and plaster of paris [ 

(3) Amount of water used in mixing \-r , ^ -,. ■ 

, „ , r J .L • 1 -Laboratorv' conditions. 

(4) Temperature of room and materials j -^ 

Fig. 23 is another of M. Garj^'s diagrams showing the change in thermal effect 
with setting of a cement as procured by varying proportions of the mixing water. 

The effect of aeration on a cement is so marked that the comparison of the four 
specifications for this may well be considered here. 

TABLE IX. 

SPECIFICATIONS FOR PORTLAND CEMENT. 
Aeration. 
"British. For all tests involving mixing, except setting time. Aeration period 24 hrs. 
U.S.A. I 
French. None. 
German, ) 

As will be seen Great Britain has the only specification insisting on aeration, and 
it is only in the latest specification (1920) that the aeration before " Setting Time " 
test was not made compulsory-. 

The effect of aeration on the setting time is well shown in Table X., taken from 
data of Mr. L. Gadd. 

TABLE X. 
Effect of Air and CO 2 on Setting Time (L. Gadd).* 





Before. | 


After. 




C02%. 


H20%. 


Initial 
(mins.). 


Final, 

(mins.)! 


C02%. 


H,0%. 


Initial 

(mins.). 


Final 

(mins.). 


Pure dry air . -29 
Moist air free 

from CO2 . '41 
Moist COj . . 1 -41 


1-45 

1-98 
1-70 


92 

85 
105 


257 

325 
315 


•3 

•43 
312 


1-41 

2-19 
1-85 


80 

120 
4 


260 

375 
10 



It will be seen that generally 

Pure dry air does not materially affect the setting time. 
Moist air [free from CO,) — retards the setting time. 
A/o/s/ CO2 much shortens the setting time. 

So the effect of aeration generally may be either to hasten or retard the setting, 
depending on the amount of CO, present. 



Trans. Concrete Institute, 1913. 



227 



R. E. STRADLING. 



[CDNCKETEJ 



Some data of Mr. H. K. G. Bamber * is extremely interesting and important as 
giving the effect of storage in cements where setting times have been controlled by the 
manufacture in various ways. 



'aemwo time- 



A 


\ 








i 










1 


Cn 


r,»w ^u=T \ > 




^ 



'/j f«4sif<», i-»j" i-enc 



■ 


SeTT>N4 Tifve c^ %, G^pto-" ■»• PuMTetj. dp 


"•.n.c »ooeo 


- 






/ 1 V 






■ 


' / 




^' ; \ ^.G,|»„^(U.. ) 




fT\^\ 


/ 


J\j \^i-l>.Jt,o(-P-..^(>"f'-') 


^ 


/ ^*^*^ 


I , , ,' 'i" 1 1 




1 J^/ A. .t.- J- i, -/ g 




Fig. 22. Setting Time Variations, Curves Plotted from Data of Prof. R. K. Meade. 

TABLE XI. 

Storage and Setting (H. K. G. Bamber). 
(Clinker contains o -6 % SO3.) 





Setting Time (mios.). 




Without Aeration. .\£ter 48 hours' Aeration. 




Initial. 


Final. Initial. 


Final. 


When ground .... 
After 3 weeks .... 

„ 8 , 

.,26 


Instantaneous 
I 


5 Instantaneous 
3 1 I 

3 : \ 

3 J 


3 
15 
10 

3 



228 



* Trans. Concrete Institute, 1909. 



r V, constructionaCI 

[t^ EMGIMF.F .P 1 NO — J 



PORTLAXD CEMEXT. 




Fig. 23. Prof. Gary's Curves showi.vg Variation of Ther.mal Changes on setting of 
A Cement by using v.\rying proportions of Mixing Water. 

Table XI. shows a cement as ground. The chnker is untreated in any way and 
the set is practically instantaneous even after twenty-six weeks' storage. 

The effect of aeration is also shown and indicates the chaotic type of results usually 
experienced due to ordinary aeration. 

TABLE XII. 
Storage and Setting (H. K. G. Bamber). 
Cement treated with i;} % gypsum (contains about 1-3 °o SO3). 



Setting Time (mins.J 



When ground 
After 3 weeks 



26 



Without Aeration. 


After 48 


hours' Aeration. 


Initial. 


Final. 


Initial. 


i Final. 


65 


330 


2 


20 


69 


240 


I 


4 


I 


3 


2 


D 


2 


60 


2 


3 



The next Table, XII., shows the same chnker ground and treated with i J per cent, 
of gypsum. 

It will be seen that after eight weeks storage it has practically returned to its 
original quick set and that forty-eight hours' aeration produces similar results. 

The danger of keeping this type of cement on a job is obvious. 

TABLE Xin. 

Storage and Setting Time (H. K. G. Bamber). 
Same clinker a.s Tables XI. and XTI. ground in presence of steam and J °o gypsum added 

(contains about -95% SO3). 







Setting Time (mins.). 






Without .deration. 


After 48 


hours' Aeration. 




Initial. 


Final. 


Initial. 




■- Final. 


When ground .... 
After 3 weeks .... 

,,8 

„ 26 „ .... 


55 

58 

50 

155 


255 
320 
410 
510 


40 
48 

55 
60 


195 
260 

390 
380 



229 



R. E. STRADLING. 



KDNCBETFJ 



The next Table, XIII., shows the same cUnker ground in the presence of steam and 
then only | per cent, gypsum added. 

It will be seen that this treatment produces a much more " stable " cement as 
regards setting time. 



TABLE XIV. 
STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 

Soundness. 

British. LeChatelier apparatus. 24 hours in cold water, then 6 hours boiling. Expansion 
not to exceed 10 mm. after 24 hours aeration previous to test. If it fails this test 
further aeration for 7 days — then expansion is not to exceed 5 mm. 
U-S.A. Pats on glass, 3" diam. V' thick in centre, tapering to thin edge. Stored in moist 
air for 24 hours. Then in steam at 98^-100° C, i" aboveboilingwater for5 hours. 
Any distortion shows unsoundness. 
French. Cold test. Pats 10 cm. diam. 2 cms. thick at centre, tapering to edges. 
Hot test. Le Chatelier. 

{a) Sea work. Pats and test pieces in moist air for 24 hours. The pats then 
immersed in sea water. 

Hot test. In boiling water for 3 hours, expansion not to exceed 5 mm. 
(6) Not Sea work. 

Hottest. Inmoistairfor24hours, then boiled for 3 hours at 100° C. Expan- 
sion not to exceed 10 mm. 
German. Pat of neat cement kept moist for 24 hours and then immersed. It should show 
no distortion or blowing (this should appear after 3 days and 28 days' immersion 
is sufficient in anj' case). 



Soundness. 

Table XIV. shows the various specifications for soundness. 

The cliief is undoubtedly the Le Chatelier, though only the British and French 
specify this method. 

This is the only British method, the French have also the cold pat test as shown. 

This cold pat test is the only German test. The Americans use a pat test but 
subject it to steam. 

^^^lat the cause of unsoundness is cannot definitely be stated. There are probably 
many contributory causes. 

Those that may cause unsoundness in the Chatelier test may not cause unsound- 
ness in the work. 

e.g. It is not at all certain that coarse grinding of a cement will necessarily cause 
disintegration in a mass of concrete, though it has been shown to be sometimes the 
cause of excessive expansion under the ChateUer test. 

There are various chemical compounds in the cement which may combine, if air 
has access, to form compounds which expand in formation. 

e.g. Various sulphur compounds may combine ■\\ith compounds of alumina to 
form the so-called " sulpho-aluminate " ; again, a sulphide may combine with iron in 
the presence of air to form various compounds which have a larger volume than those 
from which they originated. 

It is probably from fear of tliis type of action that the SO3 content of a cement is 
given an upper limit in most specifications, though this limit is certainly arbit^ar^^ and 
the only reason which can be shown for adopting these limits is, that cements containing 
up to these percentages are certainly sound, as far as our experience has gone at present. 
Far higher percentages of SO3 than that allowed by the British standard specification 
quite satisfactorily pass the Chatelier test. 

Table XV. gives the various specifications for chemical composition. 

230 



1 



CX3NSTPUCT10NAL 
ENGTNEEBXNG — ; 



PORTLAND CEMENT. 



'British. 



U.S.A. 



French. 



TABLE XV. 

STANDARD SPECIFICATIONS FOR PORTLAND CEMENT. 
Chemical Composition. 

Ratio (in chemical equivalents) 

* CaO not greater than 2-85 

SiO, + AI2O3 nor less than 2-0 
Insoluble residue not greater than i -5 % 
MgO not greater than 3% 
SO3 „ „ „ 275% 

Loss on ignition not greater than 3% 
Loss on ignition not greater than 4% 
Insoluble residue „ ,, ,, o-8% 
SO 3 not greater than 2 % 
MgO „ „ ,, 5% 
Sea work. SO3 not greater than i-5% 
MgO „ „ „ 2% 

AI2O3,, „ „ 8% 

Not more than a trace of sulphides. 
Hydraulic coefficient. 



German. 



SiO, + AloO, ^ , , , , , 

?— ^ — ^-^ - to be not less than -47 

CaO + MgO 
For AI2O3 content of 8% with decrease of 
Not sea work. SO3 not greater than 3% 
MgO „ „ „ 5% 

A1203,, ,, „ 10% 

Not more than traces of sulphides. 

CaO 

Ratio, bv weight -^.^ — , — irrr^ 

SiO, + A1,0, 



•02 °o for each i°o below 8% 



Not less than r-j 



SO, not greater 



+ Fe203 
Not greater than 3 % additions. 

MgO content (after heating to redness) not greater than 5 'Na- 
than 2^%. 

This requires more discussion by chemists than engineers. It shows liow httle 
really exact knowledge exists on this subject when the ver^' wide variation between 
the various specifications is noted. 

Tables XVI. and XVII. give two typical analyses, one of an average sample and 
the other of one high in sulphur content. Both these cements were perfectly sound 
under the Le Chatelier test, although it should be noted that the second sample 
would be rejected under all the specifications considered. 



TABLE XVI. 

% 

Silica (SO3) 20-73 

Insoluble matter -83 

Alumina (Al^Oo) . . - . . . 7-80 

Ferric Oxide (Fe^Og) 1-92 

Lime (CaO) 62-40 

Sulphuric Anhydride (SO3) . . . 1-86 

Magnesia (MgO) -96 

Carbonic Anhydride (COo) I 

Water (H2O) " 1 ' ' ' ^'^^ 

Alkalies and loss -15 



TABLE XVII. 

% 

Silica (SO3) 20-52 

Insoluble matter 0-92 

Alumina (AIO3) 7-32 

Ferric Oxide (FegOj) 3-31 

Lime (CaO) 58-19 

Sulphuric .\nhydride (SO.j) . . 3-75 

Magnesia (MgO) 2-07 

Carbonic Anhydride (CO,) ) 

Water (H^O) , • • • 3 44 

Alkalies and loss 0-48 

100 -OG 



TABLE XVIII. 

SPECIFICATIONS FOR PORTLAND CEMENT. 
Density or Specific Gravity. 
'British. Not required. 
U.S.A. Not less than 3-10 (white Portland 3-07). 

Can be retested after ignition. Not used unless specially demandeti. 

* The proportion of lime shall be calculated allowing for proportion combining with SO3 



R. E. STRADLING. 



lOQNCBETEJ 



French. Weight /litre used. Poured into cylindrical litre vessel (lo cm. high) through 
funnel. 

(a) Sea work — to be at least 1200 gms. 

(b) Not sea work ,, ,, ,, 1 100 gms. 
German. Not required 

The S.G. is only now rec]iiired in the I'.S.A. specification, and tlie lYench one stili 
specifies weight per litre. 

The modern opinion seems to be that the test is of no practical value. 

It was thought at one time possible to detect bad burning and impurities by this 
means. 

Summary. 

It is now perhaps worth while trying to summarise tlie essential tests as considered 
from the conditions laid down in the opening paragraphs. 

These paragraphs are repeated here for convenience : 

(i) Shall give a real indication of the suitability of the cement for work in hand 
(setting time, soundness, strength). 

(2) Shall be independent of the personal equation. 

(3) Shall indicate quality in the shortest possible time. 

Then all these must be considered from the two standpoints of (i) works tests; 
(2) laboratory tests. 

For all these tests a mixed cement pat is required ; this at once introduces the 
question of the amount of water to be used. This appeals to the writer as one of the 
most important points. Britain is the onlv country of these four which has no definite 
test for this. 

Personally the Boehme hammer test appeals to the writer as being the most im- 
personal of the methods given though the " Vicat " plunger is simpler. 

Then some definite relationship is required between the amount to be used for 
neat cement and the amount to be used for cement and sand. 

This could be laid down in a way similar to that of France or America. 

All the other tests are really dependent upon this point. 

Setting Time. — For laboratory methods the Thermal measurements should 
indicate more fully what is occurring. For a works test and also as an auxiliary 
laborator}' method the Vicat needle is quite suitable. 

Soundness. — Whilst our knowledge of the causes of this is so vague as at present, 
the Le Chatelier test probably gives the maximum amount of information and appears 
certainly on the safe side and takes a short time (two days). 

Strength. — The strength of a cement and sand mortar is all that is required, and 
the elaboration of a compression test seems at present scarcely required. Some 
mechanical means of ramming would appear to be advantageous to reduce the personal 
equation as much as possible. 

The type of testing machine requires careful selection. Some of the older types 
are quite untrustworthy. 

The trouble with the strength tests is the time required. It is verj^ rarel}" a cement 
can be held up twenty-eight days before use. 

All these tests as noted (except thermal) could with proper care be performed on 
the site of ^vorks if the percentage o"f water required could be mechanically obtained 
and the temperature conditions ensured. These two points are really the greatest 
difficulties on a job and have been the cause of more complaints as to the quality of 
cements than anything else. 

Suggestions as to Procedure under Present Conditions. 

It is suggested that probably the soundest method of specifying a cement in 
England at present is to specify purchase from a maker who wall guarantee each 

232 



U^'^I^^^^ PORTLAND CEMENT. 

consignment to be up to British Standard Specification and \\-ill send a testing certificate 
with it. Most firms will now do this. 

On arrival on the job, each consignment may be tested for setting time, the 
Chateher soundness, and fineness. If these are satisfactory there need be little fear of 
strength being AVTong. The only test for strength required is the cement and sand, 
and this should be done in a properly equipped laboratory and by trained workers! 
It is suggested that it might be advisable to send a sample of, say, every other consign- 
ment on a small job, or ever>- tenth on a very large job, for testing completely at a 
recognised laboratory. 

The taking of the samples is \-ery important and should if possible be done at the 
manufacturer's works. In any case, air-tight sample cases should be used and should 
be despatched to the laboratory with the least possible delay. 

The points to guard against if purchase is made from a manufacturer of high 
reputation are mainly two. 

First, that the certificate supplied is reporting on British Standard Specification 
Tests, and that all these are satisfactorily passed. 

Second, that no interchanging happens between leaving the manufacturer's Avorks 
and arrival on the j ob . This is sometimes a real danger . The writer had an experience 
of this just before the war where a local agent in another part of England filled bags, 
stamped with name of a well-known firm, with a natural or Roman cement of extremely 
bad quality. This arrived to the writer for test, and was, of course, rejected. The 
matter ended with a newspaper apology from the agent. 

" CONCRETE AND WATER ENGINEERING. 

Some mterestmg particulars of, and comments on the use of reinforced concrete in 
reservoirs etc., were given in the course of a number of papers and the discussions 
thereon at the recent ^^ inter ]Meeting of the Institution of \^'ater En'^ineers 

Detailing their experiences at Nuneaton, where the waterworks a're built on 
the outcrop of the North Wanvickshire coalfield, and are, therefore, particularly liable 
to damage from subsidence, Messrs. F. C. Cook and R. C. Moon said a brick pumping 
station and reservoir had been rendered unusable through cracks occurring owinS 
to the operations of the Colliery Company, but a 500,000-gallon reservoir of rehiforced 
concrete, built in 1906, had shown no evidence of damage whatever in spite of the 
fact that it had sunk nearly 4 ft. owing to the foflndations subsiding. In the case 
of some new reinforced concrete filter beds, although the subsidence amounted to 
4j ft., no structural fractures had occurred. In the subsequent discussion Mr \ B E 
Blackburn said that as the result of his experience on the North-East Coast in dis- 
tricts where considerable subsidence had occurred over the magnesium limestone 
area, he had come to the conclusion that reinforced concrete was the only practicable 
material for reservoirs on unstable foundations. 

Mr. George Mitchell (Water Engineer, Aberdeen), m the course of a paper on 
economy m design of waterworks, said concrete dams built in separate lengths with 
-suitable joints had many advantages over masonry dams, were cheaper and did not 
take so long to construct. He expressed the opinion that there was considerable 
scope for reinforced concrete dams of the inclined deck or multiple arch type althou-h 
H f there appeared to be only one example of this type of dam in Great Britain 
He ooked forward to the practical disappearance of brick and masonry in water- 
works such as had already taken place in dock, harbour and canal engineering He 
wa.s also very favourably impressed with reinforced concrete pipes • the United 
States Department of Irrigation had used reinforced concrete Mater pipes to a very 
large extent during the past ten years which had given excellent results and showed 
no signs of deterioration. He had also successfully experimented with the jointing 
of iron pipes with cement. Reinforced concrete was economical for roofing and 
reduced the oad on the floors ; for the latter, water-tightness would be most economi- 
cally secured by the use of concrete with a waterproof face. Replying to points raised 
in the discus.sion, the author said he thought the joints of reinforced concrete pipes 
were their strongest parts. His references to cement joints for iron pipes were to 
open socket joints, not turned and bored joints. 

D 

233 



HOUSE AT WHITELEAF. 



[CONCBCTE] 




CONCRETE COTTAGE 
CONSTRUCTION. 



Ji;;^^^ 



HOUSE AT WHITELEAF. 

An interesting experiment in concrete building has recently been carried out at 
Whiteleaf, Princes Risborough, by Mr. T. G. Davidson. During the war M r. 
Davidson had occasion to use chalk-cement concrete, and he was so impressed 
with the excellence of the results which he obtained, that he determined to con- 
tinue the use of it in England. In common with other experimenters in this 
form of wall construction, it was soon found that the secret of success lay in the 




X i 

(•1 iV 



\' toi~^ 



iiiE 






c 



T~Ol 



D 




Fig. I. Details of Shuttering. 

shuttering, and to this Mr. Davidson gave considerable time and thought which 
has resulted in a shuttering of remarkable simplicity and efficiency. 

The following description of the shuttering should be read in conjunction 
with Fig. I. Sketch E shows a portion of the shuttering in position on the wall. 
It consists of boards made up into two or three varying lengths. Accurately 
drilled longitudinally through the boards near the top and bottom edges are holes 
of sufficient size to accommodate | inch steel rods. Where several lengths of 
shuttering are erected next to each other, each rod projects a small distance into 

234 



E 



CONSTBUCTIOMA 
EiSGlME£RlNG 



m 



HOUSE AT WHITELEAF. 



I 

o 






< 



< 

H 

H 
O 




D 2 



235 



HOUSE AT WHITE LEAF. 



[0C8SCBETEJ 





Figs. 3 and 4. View of Finished House at Whiteleaf. 



236 



[&^?.^S[{.^^ HOUSES AT AMESBURY. 

the adjacent board, thus maintaining true ahgnment. At intervals on each 
board notches are cut and as the rod is passed through these a looped wire is 
threaded on, in this way so soon as any concrete is tamped between the boards 
they are held rigidly in position. Great care is taken in making up these wires, 
and for this purpose a special adjustable jig is made (see Fig. C), so that the length 
of each wire loop is identical for any one thickness of walling. In this way the 
stress is equally divided amongst the wires which are all kept equally taut, 
thus ensuring a plumb wall. The shuttering is a climbing one, and so soon as a 
piece of walling is completed the lower rods are withdrawn and the boards hinged 
up on the upper rods. The wires are left in the wall, being cut off flush as the 
work proceeds. Sketch A shows a rammer used on the chalk-cement concrete 
house, and B is a section through the piece of wall and shuttering ; the section 
being taken through the notches it shows the rods passing through and the wire 
loops around them. It will be seen that in this case the shuttering is made up 
of three thicknesses of timber. Sketch D shows an end piece, iron angle pieces 
are attached to the board between which the shuttering fits. Where it is required 
to stop off a piece of walling, a board is inserted between the shuttering and held 
in position by fixing a temporary fillet as shown in sketch E. Mr. Davidson has 
patented his shuttering, which is known as the Self-Mounting Shutter. 

Fig. 2 shows plans and elevations of the house. The thickness of the outer 
walls should be particularly noted ; these are i ft. io| in. up to the first floor, 
where they are reduced by the, width of the plate, 4^ in., to 18 in. By adopting, 
such a method of building it is possible to obtain the fine effect that is the result 
of building with such a thickness ; it forms a particularly welcome change from 
the growing tendency to make walls ever thinner and thinner until they become 
little more than a layer of asbestos sheeting. Another distinct advantage of 
the thick wall, apart from the delightful appearance of deep windows and door 
soffits, is the warmth in winter and the coolness in summer that such a protection 
affords. Views of the house are shown in Figs. 3 and 4 ; it will be noticed that the 
shuttering has been adapted to irregularities of outline, and that it has not been 
necessary to adhere to the box shaped plan with the lid roof. The lines of the 
shuttering are faintly discernible on the walls. 

CONCRETE HOUSES AT AMESBURY. 

At Amesbury several concrete cottages have been erected by the Ministry 
of Agriculture and Fisheries under the direction of the Scientitic and Industrial 
Research Department. Figs. 5 and 6 show a chalk cement concrete cottage. 
The mixture employed is 20 to i, and no water is added, the natural moisture 
in the chalk being sufficient. The walls, which are 18 in. thick, are w^orked and 
tamped in a similar manner to pise walls ; the ramming process will be seen in 
Fig. 5. In the case of this particular house the brick plinth was taken to an 
unnecessary height, all that is required, however, is a solid ballast concrete wall 
to damp-proof course level. It will be noticed that the stacks are constructed 
in the same material and not in brickwork. The outside of the main building 
is cement rendered ; it was decided, however, not to pursue this course for the 
outbuilding to which no protective coat has liccn added. The shuttering 
employed is one devised by the Department Officers. 

Fig. 7 is a reinforced concrete house also built by the Research Department, 

237 



HOUSES AT AMES BURY. 



[CQNCBEJEJ 




By permission of the Building Research Board. 

Fig. s. Chalk Co.vcrete House at Amesbory showing SHUrxEaiNG. 




By permission of the Building Research Board. 

Fig. 6. Chalk Co.wrete House at A.wesbury. 



^38 



1 



CON5TRUCT1CSS. 
EMGfMEXRlNO 



[aEI 



HOUSES AT AMESBURY. 



The walls are solid, without a vertical damp-proof course, and particular note is to 
be taken as to the tendency towards condensation which this building may exhibit. 
The roof is built up of reinforced trusses between which is Hy-Rib expanded 




By permission of the Building Research Board. 

Fig. 7. Reinforced Concrete Cottage at .\mesbury. 




By permission 0/ the Ministry of Agriculture and Fisheries. 

Fig, 8. Chalk Concrete Block House, .\mesbury. 

metal covered with concrete and laid to a fall, the chimney stacks are of concrete, 
hkewise the risers to the staircase, and the first floor, in fact the use of timber 
has been reduced to a minimum. Fig. 8 illustrates a house built by the Ministry 
of Agriculture and Fisheries. The method employed here is chalk concrete 

239 



HOUSING AT CHEPSTOW. [CDNCRETE ] 

blocks. These blocks were made in the ordinary way in a " Dri-crete "machine, 
the mixture being 12 of crushed chalk to i of cement ; an ordinary cavity wall 
construction is used. No protective covering has been placed over the outside 
surface and in the illustration tlie joints of the block are clearly visible. This is 
being done in order that the weather-proof qualities of the material may be tested ; 
it is possible, however, to add a protective coat should this prove necessary, 
and the brick window heads and sills have been set with a slight projection beyond 
the block face for this purpose. 

All these experiments in chalk concrete construction are of great interest 
and may prove of real value. The proportion of cement is so small, that where 
chalk is obtainable on or near the site the method of building should be a cheap 
one. In both the 20 to i rammed chalk and in the 12 to i blocks no water is 
added to the moisture, it being found that the natural moisture in the chalk is 
sufficient hydration. Experiments have also been made in chalk-pise without 
the addition of cement, in this case a certain amount of soil is added. This 
matter, however, is one hardly coming within the province of this article. 

CHEPSTOW HOUSING. 

In our issue of June, 1920, there appeared a detailed account of the housing 
developments at Chepstow and the surrounding villages, which constitute such 
a striking example of concrete work, perhaps one of the most extensive and most 
successful in England. The vicissitudes through which the shipyards have 
passed have been many, and when at the termination of hostilities in 1918 the 
Government, who had by then acquired all the shipbuilding interests in the 
districts, abandoned this great scheme, there seemed a danger that the yards, 
and consequently the fine new villages, would become abandoned. Fortunately, 
however, the Monmouth Shipping Company, which was formed in the spring 
of last year, took over the yards, together with almost the whole of the new 
villages of Hardwick and Bulwark, both on the outskirts of Chepstow, and the 
smaller village of Pennsylvania on the Ledbury side of the river. The price 
paid was ^f400,ooo for the three villages, comprising some 475 houses. An 
aeroplane view of Bulwark is shown in Fig. 10. The main road running through 
the centre is The Avenue ; a fineh* planned road fifty feet wide. Ultimately this 













'^ 




i^ *^ 


k 


1 


;<?*-' <,.^^'f^ 


H 




%■ --f— t| 


1^ 


^ 




^^H 






IL 


i: 




Hj 


f^.v|..- .- 


-,- 






3 


pp^4l^^^JI_ 






^ 


f 


1 


m 


1 



Fig, 9. The Octagon, Bulwark \'illage. 
240 



g 



C0N5TBUCT10NA1J 

iryjr.rNy.F^P[^r.-;:j| 



HOUSING AT CHEPSTOW. 




241 



HOUSING AT CHEPSTOW. 



iCDNCKETEJ 



road will terminate with a circular space in the middle of which will be placed 
a band-stand. An imposing feature of the layout is the Octagon, which is clearly 
seen in this photograph, and of which a detailed view is given in Fi^^. 9. The 
aerial view shows very clearly the enhanced effect obtained by skilful grouping 
of the houses, by the formation of crescents and axial planning, so that the various 
roads terminate on some feature of interest. Another type of house is illustrated 
in Fi<f. II, and in the background of the same photograph can be seen a different 
treatment, so that it will be appreciated that the variety is very great. All 
the houses have been constructed of blocks made on Winget machines. The 
size of these has, fortunately, been kept small, so that the scale of the building 
is not destroyed. Moreover, since the aggregate is largely composed of crushed 
stone they have a warm pleasant colour. During the last two }ears the concrete 
has improved during the process of weathering, and the whole town has acquired 
a mellower and softer tone ; it is indeed fortunate that a great opportunity was 
not missed, as it might so easily have been, and instead of these buildings, which 
harmonise so well with the old stonework of Chepstow, a mushroom growth of 
hideous terraces might have defaced the landscape, one of the most beautiful in 

England. 

The rents of the houses at Bulwark vary from gs. to 25s. per week, including 
rates. The architect for the scheme was Mr. Henry E. Farmer, F.R.I.B.A., now 
Housing Commissioner at Birmingham under the Ministry of Health. The 
contractors were Messrs. Henry Boot & Sons. 




lij. II. _ _:toria Road, Bulwark. 

Chepstow Housing. 



Reconstruction in Belgium. — Although Belgium is peculiarly well placed as 
regards building materials and relatively cheap labour, the reconstruction of the 
devastated areas is proceeding very slowly. Prices are likely to fall still further, 
but even then substantial buildings will be too costly. 

For some of the farmhouses, repairs are being made of reinforced concrete, the 
outer walls still standing being used as far as possible, and internal walls being made 
of_metal mesh covered with concrete after erection. — Beton Anne. 

242 




THE CONCRETE INSTITUTE. 



THE CONCRETE 
INSTITUTE. 

MONTHLY NOTES. 

By the SECRETARY. 



RECENT ELECTIONS INTO THE INSTITUTE. 

Honorary Member :— Miss Elizabeth Frances Putz, Editorial Secretary, Con- 
crete AND Constructional Engineering. 
Members : — Albert Edward Gosling. 

Waldo Emerson Guy. 

Henrv Major Hale. 

Alfred Thomas Blakey Kell. 

Charles Robert Porter. 
Associate-Member : — Bansi Ram Seengal. 

INTERNATIONAL BUILDING TRADES EXHIBITION. April 12th-26th. 1921. 

Wednesday, April 13th, at 1.45 (for 2.0) p.m., members will assemble in 
the Welcome Club Rooms, when Mr. A. Alban H. Scott, M.C.I. , has kindly con- 
sented to organise parties to be conducted by competent guides to inspect the 
most interesting stalls. At 4.30 p.m. in the Lecture Hall, Mr. H. Kempton 
Dyson, M.C.I. , will read a Paper upon " Building in Concrete." 

Tuesday, April 19th, at 1.30 p.m., the Council of the Institute will give a 
luncheon in the Pillar Hall at Olvmpia. The Rt. Hon. Christopher Addison, M.P., 
and the Rt. Hon. Lord Riddell will be guests of the Institute. Mr. G. Topham 
Forrest, F.R.S. Ed., F.R I.B.A., and Sir James Carmichael, KB.E , have also 
been invited as guests. After lunch, Mr. A. Alban H. Scott will speak upon 
" Building Bye-Laws and Regulations." Tickets for the luncheon can be 
obtained from the Secretary of the Institute, price 6s. each, exclusive of wines, 
etc. Early application should be made. 

By the courtesy of the management the Institute is allowed to make use of 
the Welcome Club Rooms during the period of the Exhibition. 

Tickets for the Exhibition can be obtained from the Secretary of the Institute. 

CLASSES IN STRUCTURAL ENGINEERING. 

We have received the additional information as to classes in the above : — 
London County Council School of Building, Ferndale Road, Clapham, S.W., 
Mondays to Fridays, 7.30 p.m. to 9.30 p.m., according to subject. 

Mechanics of Building and Strength of Materials, Drawing and Design of the 
Structural Steelwork of Buildings, Reinforced Concrete and Structural Engineer- 
ing applied to buildings. 

Lecturers :— Messrs. E. G. Beck, Wh. Ex., A. M.Inst.C.E. ; H. Kempton 
Dyson, M.C.I. , M.Int.Assn. Testing Materials; R. Graham Keevil, M.C.I. , 
A.M.I.Mtch.E., and W. Russell. 

LECTURES AT THE CONCRETE INSTITUTE. 

Thursday, April 28th, at 7.30 p.m.. Paper by Prof. F. C. Lea, D.Sc, on 
" The Elastic Modulus of Concrete " (Lantern). 

-=43 



J. ALLEN HOWE. [CDMCBEJE 3 

Thursday, Ma\' 2()th, Paper by Mr. Lawson S. White, M.C.I., on " Land 
Subsidence and its effect on Concrete and other Structures." 

The Annual Genkral Meeting will be held on Thursday, May 26th, 1921, 
at 7.30 p.m., prior to the last-named Paper. 

CONCRETE AGGREGATES. 

We publish a letter received from one of our members, as follows : — - 

" May I be permitted to correct a slight inaccuracy in the valuable particulars 

of local aggregates now being published in Concrete and Constructional 

Engineering. 

" In the December, 1920, issue, p. <So4, it states : — 

" ' Cornwall. The felspar obtained from tlie refuse heaps of china clay washings 
is contaminated with clay, tlius making it unsuitable for first-class concrete.' 

" These refuse heaps are not composed of felspar contaminated with clay, 
but of quartz contaminated with disintegrated felspar (china clay), mica, etc., 
but apart from this little inaccuracy the classification is correct, and the sand is 
certainly not suitable for first-class concrete. 

" In many districts, however, this material is to be found in beds where it 
has been deposited by the rivers, and having been washed for centuries, is free 
from all impurities. 

" The writer has such a high opinion of the sand from these sources that he 
is now sending it from Cornwall to S. Wales for use in important Reinforced- 
concrete structures. 

(Signed) " GowER B. R. Pimm." 

M.C.I., A.M.Inst.C.E. 

(34) Farnham (Surrey) :— Gravel and sand, containing 12 per cent. loam. (R.C.B.)* 

(35) Felixstowe (Essex) : — Beach shingle. Excellent. (R.C.B.) 

(36) Flint (N. Wales) : — Crushed spar from lead mines, containing sulphur and other 

impurities. (R.C.B.) 
Correction : — In the September issue, 1920, under (11) Bolton, it should read as 
"Stone" instead of " Sand." 

* K. C. Branston (see notes in previous issues). 



THE GEOLOGY OF CONSTRUCTIONAL STONE. 

By J. ALLEN HOWE, O.B.E., B.Sc, etc. 

The following is an abstract from a Paper read at the One Hundredth Ordinary 
Meeting of the Concrete Institute. 

The Paper was illustrated by lantern slides and an interesting diseussi^m 
followed. 
Mr. E. Fiander Etchells, the President, was in the Chair. 

By the geology of building stones we mean the application of geological methods to 
the study of constructional stone, and this study may be said to embrace ; — i. The geo- 
logical distribution of stone. 2. The effect of geological structures on the economics 
of quarrying. 3. The petrology of stone. 4. The chemical and physical properties 
of stone. 5. The decay and wear of stone. 6. The testing of stone. 

Clearly it is not possible here to give adequate treatment to even one of the sub- 
jects, and only a rough sketch indicating their relationships is here attempted. 

The Distribution of Stone. — There is now a markedly growing tendency in this 
country to consult geological maps when new sources of stone are required. 

But the geological distribution of stone of specific character is by no means the same 
thing as the localisation of rocks of the same geological age. It does not follow that 
a formation in which a good stone is found at one spot will contain stone of a similar 
quality elsewhere. Portland stone, to take a familiar example, occurs in the Portland 

244 



&^?.fNl^NG^ THE GEOLOGY OF CONSTRUCTIONAL STONE. 



fonnation, which is traceable from the Isle of Portland to Oxfordshire, while stone of 
" Portland " quality is found only in the Isle of Portland and the neighbouring coast 
of Dorset. When the formation is followed no farther than the Vale of Wardour, 
though extensively quarried there, the type of stone is quite different, and if we trace 
the outcrops further afield we shall search them in vain for true Portland stone. 

The exploiter of stone requires, therefore, more definite indications of qualit}' than 
can usually be put upon a geological map. 

Quarrying. — When we turn to the quarrj-ing of stone we find that due comprehen- 
sion of the geological circumstances is a matter of some importance. The economic 
development of the quarry, the avoidance or disposal of waste, the drainage and cost 
of operation, as well as the quality of the product are more often than not closely related 
to these circumstances. 

Rock Types. — Rocks fall naturally into two classes, igneous and sedimentary-, 
each, from the technological as well as the academic standpoint, possessing characters 
peculiar to itself. 

The sedimentary rocks employed in construction are classable, with unimportant 
exceptions, as sandstones and limestones. 

The sand grains that normally make up the bulk of sandstones, being derived from 
pre-existing rocks, are composed of their more resistant minerals, quartz predominating. 
Some sandstones contain no other essential mineral, while others carry more or less 
felspar and mica besides accessory minerals of no technical significance. 

From the point of view of the engineer and architect the binding medium or the 
character of the bond between the quartz grains is the feature in sandstones requiring 
most attention. The grains are usually held together by secondary mineral growths 
composed of materials derived either in part from the grains themselves or introduced 
by mineral-bearing solutions. The best and most prevalent binder is silica ; others 
are calcite, iron oxides, clay, and in rarer cases a variety of other minerals ; frequently 
several of these binders are operative in the same stone. A sandstone with a pre- 
dominant calcite binder behaves under chemical attack like a limestone, but without 
that stone's good qualities. 

Besides the nature of the binder the state of aggregation of the grains is an important 
characteristic ; great diiferences in porosity and grain cohesion are caused by the 
presence or absence of an inert filling between the grains and by the degree of compression 
and compacting of the grains. 

The majority of limestones employed in construction were origmally organic in 
origin, but they have usually undergone internal changes, such as the partial solution 
of the calcareous shells and fragments accompanied by re-crystallisation of the calcite. 

Two types of limestone deserve special notice, the oolites and the magnesian 
limestones. Oolites are built up largely of rounded grains of concretionary origin ; 
stones of this kind are well-known and valued building stones. 

Magnesian limestones are composed of calcium and magnesium carbonate, the latter 
being combined with calcium carbonate as the double carbonate, dolomite, which 
tends to crystallize in well-defined rhombic crystals, giving the stone a " sandy " feel. 
Every gradation is found from a calcareous limestone with a few rhombs of dolomite 
to a pure dolomite rock. The mineral dolomite is rather more resistant to solvents 
than calcite. 

Metamorphic Rocks. — By the effect of mechanical deformation and heat any of 
the rocks mentioned above may be so altered or " metamorphosed " as to cause them to 
take on entirely new characters whicli places them in a class apart, namely, the meta- 
morphic rocks. 

One of the most important characteristics of these rocks is the fresh orientation 
and re-growth of the mineral constituents which may introduce the quality of fissility 
in one or more planes in some cases and greatly increases the toughness and strength 
in others. 

Chemical Properties of Stone. — All stones are built up of minerals of known composi- 
tion ; therefore if we can recognise the minerals that constitute a stone a"nd estimate 
their relative proportions, we can then estimate its chemical composition with sufficient 
accuracy by mere inspection. I'his can be done bv cutting a thin slice and subjecting 
it to microscopic examination. 

245 



J. ALLEX HOWE. ICQNCRETEJ 

The Disintegration and Wearing of Stone, -in all situations stone suffers more 
or less chemical disintegration. Granites and sandstones with good siliceous bond 
suffer least from chemical wear ; limestones and sandstones vvitli a calcareous bond 
suffer the most. All stones with a fissile tendency are prone to develop this character 
on exposure. Much of the superficial wear of granites and limestones is due to the 
gradual opening out of the minerals that possess a highly developed cleavage, such as 
the felspars, calcite, micas and amphiboles. 

Testing. — The two properties of stone about which we commonly require informa- 
tion are its strength and its duyability. Vox the first it is customary to investigate 
the behaviour of the stone when subjected to pressure, tension, shearing, and so on. 
An estimate of the second quality is a more complex and difficult problem. 

Taking first the tests of mechanical strength we find that the most commonly 
applied test is that of compression. Now this test, though apparently so simple, is 
beset with difficulties, and as a rule too few blocks of a kind are tested. 

How great the variability may be is exemplified in some of the test records of the 
Charlottenburg laboratories ; thus, in 60 different kinds of granite, test pieces from the 
same quarry showed an average individual difference of 31 -6 per cent. 

2 kinds showed differences of 2 to 10 per cent. 

6 ,, ,, ,, II ,, 20 ,, 

23 ,, ,, „ 21 ,, 30 

21 ,, ,, ,, 31 ,, 40 ,, 

6 ,, ,, ,, 41 ,, 60 ,, 

and some gave even higher differences. 

Discrepancies of a similar kind are shown in the results for other kinds of rocks. 
Merrill gives figures showing the following results for the three principal stone 
types, in lb. per square inch : — 

^lax. Min. Average. 

Granites, 100 tests 28,000 6,117 17,000 

Limestones, 80 tests 25,000 3.550 14,000 

Sandstones, 132 tests .... 20,000 1.149 8,500 

The transverse strength of stone, or its resistance to bending should be, as experience 
in buildings proves, a more useful test though it is not so frequently performed. The 
Canadian tests provide the latest long series of tests available. 

Baldwin Wiseman has published results for a number of British stones. 

Tests on the elasticity of rocks have not been ver^' numerous, probably the best 
are those of Adams and Coker. A few British stones were tested by Prof. Hudson 
Beare. 

In spite of the fact that stones in buildings yield to shearing stresses more often 
than to pressure, comparatively few results of shearing tests are available. 

The tensile strength of stone has been to a great extent ignored, mainly on the 
quite reasonable ground that stones within a structure are practically always in a con- 
dition of pressure and rarely of tension. Hirschwald, however, has shown that very 
useful results may be obtained by the tensile test, carried out in the same manner as 
for cement. 

Determination of the specific gravity is required for the measurement of the stone's 
porosity, a very important character, for it has been well established that the more 
porous stones are the least resistant to the evil effects of moisture and frost. In this 
connection we have to remember the difference between the larger and the smaller pores. 

Neither the water absorption nor porosity must be confounded with the permeability, 
for this depends not alone on the amount, but on the character of the pore space. 

The influence of the softening effect due to absorption of water may be expressed 
as the ratio of the work to be done on the wet stone to that done on the dry stone when 
tested under similar conditions. This influence has been tested by compression, tension, 
grinding, rumbling, boring and the sand-blast. In all types of stone there is a distinct 
decrease in strength in the wet state, and figures obtained by the different methods of 
testing yield fairly concordant results. 

The action of frost on stone is in some situations a familiar cause of disintegration, 
and it has been the subject of much experimental work. 

246 



^ EMGllSEXKING 



^g THE GEOLOGY OF CONSTRUCTIONAL STONE. 



The attack of frost on stone is affected by the presence of cracks, by the size of 
the pores and the total amount of pore space, but most of all by the content of water at 
the time of freezing. It has been conclusively proved that the stones above the ground- 
line in buildings hardly ever contain even half their maximum content of water. The 
pores must be over nine-tenths full if frost is to exert an effective pressure ; consequently 
it is the fine pores — those that hold the water — which count in above-ground structures, 
and the coefficient of saturation is now being generally accepted as the most convenient 
criterion of the frost-resisting quality of a stone. 

The corrosive action of strong acid vapours and weak acid solutions has often been 
tried upon stone. Here again the action is too drastic if the acids are strong and is too 
slow if the solutions are weak. 

Parker, who carried out the Canadian tests, has found the following procedure give 
results which he pronounces satisfactor\'. The stone is dried at ioo° C, measured and 
suspended in water through which a current of COg is passed ; the water is renewed 
ever>^ four days, and the process is continued for four weeks. At the conclusion of the 
test the stone is washed in distilled water and rubbed lightly over with the fingers, 
dried and weighed, and the loss per square inch determined, . 

A simple test employed by Hirschwald, capable of yielding useful information on 
the permeability and structure' of the softer stones, is that of soaking equal sized test 
pieces in an alcoholic stain. After drs'ing, the stones are cut open and the character 
of the internal staining is observed. 

The " hardness " of stone, or its resistance to mechanical wear, has been tested 
in a variety of ways ; for example, by grinding with abrasive on a rotating disc, by boring, 
by the sand-blast, by scratching and by the Brinell test. 

In the case of road-metal, and the tests are also applicable to material for concrete, 
certain tests have been more or less standardised in America and this countr>\ For 
the " attrition " test a rumbling machine of the Deval type with four cylinders is used. 
The charge consists of 1 1 lb. (5 kilos.) of stone, composed as nearly as possible of 50 
pieces, and the drums are given 10,000 revolutions at the rate of 30 per minute. In 
the wet test i • i gallons (5 litres) of water are put in along with the stone. The percentage 
loss is estimated from the amount of material removed that will pass a sieve of one- 
sixteenth inch mesh. The French coefficient of wear is — i- — — . 

% loss of weight 

For the " abrasion " (or hardness) test a machine of the Dorry t^^e is employed. 
Cut cylinders of stone, i in. long and i in. in diameter, are maintained at a constant 
pressure against the surface of a cast steel disc fed continuously with crushed quartzite, 
and the loss of weight determined after 10,000 revolutions at about 28 per minute. The 
American coefficient of " hardness " — 20 — loss of weight in grams 13. 

Toughness is measured by the behaviour of the stone when tested in the Page 
impact machine. The test pieces are cylinders cut as for abrasion. The hammer of 
the impact machine weighs 44 lb. (2 kilos.) ; for the first blow it is allowed a fall of 
0-4 in. (i cm.), and this is increased by the same amount for each succeeding blow until 
the stone fails. The number of blows is the measure of " toughness." 

Hirschwald and Brix studied the behaviour of road-stones when subjected to direct 
pressure and they measured the amount of the different sizes of stone produced. The 
results were also compared with material taken from the roads. 

In the case of waterbound roads the " cementation " test is of interest. The 
method adopted by the National Physical Laboratory is to grind the stone in a standard 
ball mill, and from the material prepare six briquettes under a pressure of 1,880 lb. 
per square inch. These are dried for 24 hours and then broken under the Page impact 
machine. 

Having dealt with some of tlie methods of testing stone, though in a very imperfect 
manner, we may ask ourselves how far do these tests go towards providing a reliable 
measure of the comparative merits of stone for use in different types of structure and in 
tliverse situations ? 

As regards the purely mechanical properties, the tests, when performed under 
standard conditi(>ns, undoubtedly yield results that may be of value in specific cases. 
At any rate, witli tlicsc mechanical tests we have something we can measure in a straight- 
forward way. 

247 



J. ALLEX HOWE [CC^^BETEJ 

But the mechanical strength has often httle to do with the durability of stone, and 
when we set ourselves to measure this quahty we are faced with a series of imponderabilia, 
or at least, with a number of factors extraordinarily difficult of evaluation. 

Pfaff , Hilger, Schutze. Bissinger and others have carried out long-duration weather- 
ing tests on stone, and thirty years have been reckoned none too long a period for such 
investigations to bear fruit. But by far the most detailed, logical and scientific attempt 
to find a solution to the forecasting of weather-resistance and durability is to be found 
in the elaborate labours of Hirschwald. His mode of attack is theoretically sound, 
but the complexity- of the scheme is appalling. 

Rosival's method of determining the weather-resistance was based upon his plani- 
metric measurements of the individual mineral components combined with the deter- 
mination of their respective hardnesses. Thus, he took the theoretical hardness (H) = 
Px^*\ """ Pi^^i "^ Pz^h ■ ■ ■ ^ pJ'm- where p^, p.^, etc., were the percentage volumes of 
the minerals and /i,. h^: their respective average hardness. The effective hardness 
(A) was determined from the loss of volume after grinding the stone in a prescribed 
manner. The freshness (F) of the stone he represented as h H, while the degree of 

weathering (V) or loss of "" hardness " = — — — . 

H 

Here again, though the theoretical basis may be accepted the technical value of 

the method is out of all proportion small when compared with the latxiur involved. 

Finally one is driven to the conclusion that while it is possible to learn much about 

the qualities of stone by the methods discussed, it does not appear possible to grade 

stones according to their weather-resistance or durability by any reasonably short 

process. 

DISCUSSION. 

Sir Hemy Tanner, C,B., ia referring to the last part of the paper dealing with the weathering qualities 
of stone, said this question had been of some interest to him on many occasions when erecting buildings 
all over the country- and selecting the stone, because it was a ver\- difficult thing to find stones which 
would weather properly in various towns, especially in the smoky towns of the north, where the effects 
of weather on the stone were worse than anywhere else, even London. He had alwa>"5 endeavoured 
to find his stone somewhere in the neighbourhood in which the building was to be erected. In York- 
shire good stones could be obtained which seemed to wear very well in places hke Leeds. Bradford and 
Hahfak, but in that district they were nearly all sandstones, and many of them needed to be treated 
in order to afford some sort of protection against the weather. He had tried one or t%vo s>-stems. but 
whether they had answered or not he was imable to say at the moment. After all, we seemed to come 
back to Portland stone for the bulk of the big buildings, even in Manchester and Liverpool, and it seemed 
to be the best stone for this purpose. The great point in its favour was the ease with which it was 
alwa\-s possible to obtain the necessary" quantity. With regard to the photograph of a stone step with the 
top layer peeling off', which had been shown on the screen, a large part of the Yorkshire stone was laminated, 
and required verj- Uttle inducement to break off, but some Ycrlshire stone could be obtained with ver\- 
little lamination. That, however, was ven.- difficult to obtain, and was much dearer, but he had always 
thought it worth the money and had used it when possible rather than the cheaper \ariety. He asked 
whether the author had had experience of methods of preventing the disintegration of stones. 

Mr. W. J. H. Leverton, Lkentiate BJ.B.A^ referring to Sir Henry Tanner's remarks on Yorkshire 
stones, said he had noticed that in some cases in London they did not stand so well, and that corroborated 
the %iew that a stone stands well in its own district, but not so well in another part of the coimtry. 
Bath stone stood ver>- well in Bath, though not so well in London. With regard to the photograph shown 
on the screen and taken at Charlottenburg, in which the stones above the plinth had gone ven.- badly, 
the speaker inquired whether there was a damp course, because if not. the tendency of the dampness 
must have been upwards. 

Mr. C. H. Colson, O.B.E., said he thought the paper almost started a new era in building stone 
selection. In the past they had been practically forced to find out what had happened to various stones 
after they had been used for some time in order to select their stones, and that had been the best guide 
possible. That, after all, was more or less rule of thumb, and it seemed to him to be possible that, by 
acquiring greater knowledge of the characteristics of the various stones, the way in which the different 
grains were tailed into each other and the character of the matrix, in the futtire we may be able to evolve 
tests which would allow us, with some degree of certainty, to select building stones. \^xth regard to 
lavas, Mr. Colson said there were many difteroit lavas, and he would Uke to hear whether any were used 
in this coimtry. 

The speaker also asked the author if he would say a word or two as to what happened in regard 
to the re-crystaUisation of the surface of rocks of the neoUthic type. The upper portions of it were ver\- 
open in grain, the grain was quitfe round, and probably connected with calcite in Uttie ridges, but the 
lower pKjrtion seemed to have been formed in shallower water, possibly with a considerable amount of 
large organisms, but the whole of the interstices filled with calcite. Has this been washed down from 
the upper layers into the lower or has it been formed in the lower layers ? The upper layer was quite 
unreliable as a weathering stone, whereas the lower layer wore extremely well. 

Mr. H. F. Bladen, M.CX, said he was not familiar with the question of the wearing of stones, but he 
had been told by builders that weather made a kind of cement on^the surface of certain porous stones. 

248 



1 



^^TBucncgAij jjj^ GEOLOGY OF CONSTRUCTIONAL STONE. 



He had lived in a house at one time where the weather drove through certain stones in the front of the 
house, and when the builder told him of this, and that it would stop, he thought it was due to his optimism, 
but in point of fact the weather stopped driving through. He would like to know whether that was a 
fact, and whether it had any significance with regard to the wear of stones. 

Mr. H. G. Lloyd, referring to the freezing tests, said he would like to know whether the stones shown 
on the screen were completely filled or saturated with water before subjection to the freezing tests or 
whether thev were less than nine-tenths full of water, so that the tests should be more comparable with 
what would be likely to occur in the actual weathering of stones. 

The President asked what was the latest view as to the origin of flint, 

THE LECTURER'S REPLY. 

Mr. Howe, in replying to the discussion, referred first to Sir Henry Tanner's remarks about the use 
of Portland stone in the northern coimties. The general aspect is a sandstone aspect, and it certainly 
seemed very suitable, but it would accumulate the dirt, of which there was plenty there. There appears 
no reason whj^ Portland stone should not behave as well there as in London. From the building stone 
point of view the first thing to do rested not with the engineer, but with somebod}' else who would settle 
the atmosphere of the towns. If that were settled the whole trouble really went. The purel}^ mechanical 
properties of stone could be easily dealt with by the engineer, but it is necessary to find out what the 
stone has to suffer in a building and what it has to bear. Quite a number of points arose in this connec- 
tion, one very important factor being draughts ; they have an extraordinary effect, even inside buildings. 
Sir Henry Tanner had suggested preservatives after atmospheres, but although these merit consideration 
we have as yet hardly enough experience of the different types of preserv-atives to form a proper judgment. 
More co-operati%-e and organised investigation is still needed on this point before we can arrive at definite 
conclusions. Materials of some kind were essentially necessary, but our knowledge is still too small 
to say clearly and honestly what would be correct. 

With regard to the plinth, mentioned bj^ Mr. Leverton, that had a damp course. It was really a 
question of the position of the pavement roimd about it, which allowed the soaking rain water to lie 
there a little longer than usual. 

Coming to Mr. Colson's question as to tests, the lecturer thought he had more or less tried to answer 
that question. He had suggested what he thought w-as one of the most reasonable tests and the least 
expensive. He did not believe in prolonged and elaborate tests, they do not seem to be worth the money 
and time spent on them. As to lavas, there were very few used in this cotmtr\\ They had not much 
strength, and no one, except under extreme provocation, would think of using them, although there 
were some in the west of England and in Scotland. With regard to re-cr\-stallisation, in the particular 
case mentioned, Mr. Howe was inclined to think that in the upper part of the stone the calcite had been 
removed. Frequently the upper part had been more exposed to the weather. The calcite in rocks of 
that sort moved about with extraordinary freedom, and there was solution, re-solution and re-disposition 
taking place at any and all times in the earlier stages of formation. 

Referring to Mr. Bladen's point as to the skin on the stone and permeability, practically all stones 
in the first place were permeable to water and gases, and the latter to an extraordinary' extent, and as 
they altered by weathering the permeability decreased. Probably what happened in this particular case 
was concentration of the soluble matter in the stone, which came to the surface and clogged up, to some 
extent, some of the pores. 

With regard to freezing tests, those mentioned in the paper were carried out with stones in a saturated 
condition. The question of the amount of water is always a debatable point in this connection, but the 
only way to get real information is to have the stone either bone dr>' or really saturated, because the 
other stages are difficult to get with imiformity in the different stones. It is possible to get uniform con- 
ditions with one particular stone, but when the test is applied to stones of different character the diffi- 
culties are insuperable. Practically all testers had their specimens practically full of water, which was 
the worst possible condition for submission to a freezing test. In the natural state in the building, com- 
paratively, the stone really has not enough water to do any damage. 

The lecturer said he was afraid he did not know much about the origin of flint, although there was 
a great deal of literature on the subject. The old theories practically held groiuid yet, i.e., that a lot of 
flints had been formed in the rock in two ways, either quite early, when in the soft condition — and in 
some cases that probably was the case — and in other cases, without any doubt, they were formed at a 
later stage by the passing of silica solution from point to point and concentrating at centres which acted 
as gathering groimds for the colloid structure. 

A heartv vote nf thanks was accorded the author. 



MEMORANDUM. 

Joints in Concrete Roads. — A method of concealing the joints between each day's 
work has been .successfully adopted in the construction of a concrete road in Van- 
couver. A strip of i-in. board was placed against the face of the finished work, with 
its top 3 in. below the surface of the road surface. The new concrete was laid to 
cover the top of the board, and to connect up with the top 3 in. of the concrete already 
laid, thus forming an unbroken surface. Althougli very fine cracks have developed 
above the joints, no appreciable widening is noticeable, and as the cracks are too fine 
to permit water to percolate to the sub-grade the surface is not affected by cracks 
due to that cause. 

E 249 



REINFORCED CONCRETE IN SPAIN. [CDNCBETE ] 

REINFORCED CONCRETE IN SPAIN. 

With few exceptions the designer of concrete buildiiif<s in Spain has failed, it would 
seem, to secure any intimate relationship between his material and his treatment of 
it. Although the use of reinforced concrete as a building material appears to be most 
extensive, and to embrace buildings of great diversity of form and function, the general 
impression that is gained from the pages of a very fully illustrated brochure on re- 
inforced concrete in Spain* is that only in the rarest cases does the design of the building 
owe anything to the material from which it is constructed. For the most part the 
designs are the result of that specious movement that spread over a large portion of 
Europe, fortunately never obtaining more than the most precarious foothold in England 
(if we lose much that is good through our insular position we also avoid much that is 
bad), known as " Nouveau Art." The chief characteristic of tl^e style is a useless 
profusion of ill-designed curves. It may be asserted, by way of defence, that the 
Baroque architecture of both Rome and Spain has the same characteristic, but there is 
this difference in that the Baroque formed a natural development of the Renaissance, 
and, moreover, it was very intimately bound up with the Roman Church and its ritual, 
wliile the Nouveau Art was but a sporadic outburst of those desirous to create sensation. 
It had neither its roots in the past nor did it possess tlie virility to project into the 
future. 

As has been indicated there are, however, exceptions among the illustrations 
reproduced in the brochure, and perhaps the most notable of these is the staircase 
of a large store at Barcelona which is illustrated in Fig. i. There is without doubt 
evidence of imagination and boldness of conception in the treatment of this staircase 
which makes it monumental. It is furthermore evident that the designer in creating 
his fine sweeping curves was throughout conscious of the material in which he worked, 
for tliere is about it a plasticity which is one of tlie distinctive qualities of concrete, 
and it is doubtful if anv other medium would have yielded quite the same result. 

Fig. 2 shows an interesting architectural composition executed in concrete. 
There is much to which exception might be taken by the purist, but the combination 
of the door and the window, and the relation of the voids to each other and to the 
surrounding detail is enterprising and displays vitality. The fault lies in the pro- 
portion of the entablature to the columns. The shafts appear too weak for the super- 
imposed mass, which suffers from many unpleasant exaggerations that border on 
coarseness ; particularly is the cymatium far too heavy. 

It is often in quite small features that the influence of concrete is discernible by 
the observant ; the fact that a certain feature could onh* have been carried out by 
means of that particular material rather than any other arrests the attention. Such 
examples are all too rare in England, where the architect seems too lethargic to inquire 
into the potentialities of this new method of building, or if he use it he is content to 
handle it as he would a stone covered steel structure. An admirable example of this 
spirit of adventure occurs in a house at Barcelona {Fig. 4). Seen as a whole the 
building is thoroughly ugly and is permeated with coarse detail and senseless curves ; 
but in what other material could the projecting bay on the first floor have been so 
boldly achieved ; so much glass, spanned with such grace ? Only a material strong in 
both tension and compression can do such wonders. 

The scope of the book is large, including warehouses, shops, garages, bridges, 
concrete boats, indeed, examples of every kind of use to which the material can be 
put are included with the exception of the small house or cottage. An extremely 
well-designed water tower is shown in Fig. 3. Here not only is the general conception 
good, but the details appear to be more refined than those which characterise so much 

* Published by Messrs. Construcciones y Pavimentos, Barcelona. 



1 



CONSTPUCTICRMAL 
EMGIMIXRING — , 



REINFORCED CONCRETE IN SPAIN. 




l-'ic. I. Staircase im Largi; Store at LJarcelosa. 



251 



REINFORCED CONCRETE IN SPAIN. 



(CDNCRETEJ 








^^ymmmmmmm^K^mmij 





siriwesfsf 






Fig. 2. Entrance to a Chalet in Saria. 



252 



1 



COT^STBUCTlONAi; 
EMGTNEERING — j 



REINFORCED CONCRETE IN SPAIN. 





Fig. 3. A Water Tower at Sauapi ll. 



253 



REINFORCED CONCRETE IN SPAIN. 



[QQNCEm 



work in the book. There is Uttle evidence of the influence of national Spanisli archi- 
tecture. Here and there the Moorish element is apparent, and in certain details, sncli 
as door canopies, metal work, grilles, garden ornament, the influences of the vernacular 
can be observed. 

There is much justification for the assumption that reinforced concrete will 
eventually supersede steel work, except for roof construction, as a constructional 
system, and in order to display the advantages of the former the volume includes many 
photographs taken subsequent to an outbreak of fire in steel-framed buildings, showing 
their twisted and shrunken members crumpling the entire building in their death throes. 
Many reinforced concrete bridges are shown, and here the aesthetic superiority over 
steel work is patent ; the component members, in many examples, have a sinuous 




Fig. 4. A House at Barcelona. 

grace that could be obtained in no other material, and the daring that is displayed 
provides a thrill of intellectual pleasure. Compared with steel work, which is mundane 
and often oppressive, the light concrete span appears romantic and capable of such 
infinite development and refinement. 

The text of the volume is short ; the first three sections deal with reinforced concrete 
in a general way and its development in Spain ; these are followed by a chapter on the 
Architecture of Reinforced Concrete. In this chapter, however, the writer shows that 
he is alive to the new conditions arising from the use of the material and that the best 
results will not be obtained by working along the lines that were applicable to other 
materials. The more this consciousness is awakened the better will be the result 
Avhether the building be in Spain or in England, in America or in Germany. 



= 54 



f o, coNstkuctiotmaD 



RECENT BRITISH PATENTS. 



RECENT BRITISH PATENTS 
RELATING TO CONCRETE. 

We propose to present at intervuls partiailars of British Patents issued in 
connection with concrete and reinforced concrete, the articles being prepared by 
]\Iessrs. Andrews and Beaumont, Patent Agents, of 204—6 Bank Chambers, 29 
Southampton Buildings, W.C.2. The last article appeared in our issue of Decem- 
ber, 1920. — Ed. 

Concrete Moulds. — No. 151,692. John Woolcock and William John Stewart, 
42 Albemarle Street, London, W .1.. Accepted September 20/20. — This invention con- 
sists in a method of moulding concrete products by the employment of rubber or 
material having similar properties for the moulding surfaces, according to which 
the reduction in the thickness of the rubber under the tension of withdrawal or the 
small determined contraction of a core or other part in the absence of supporting 
means is utilised for obtaining sufficient clearance to permit separation of the moulding 
and moulded surfaces by parallel or sliding movement without damage thereto. 







I' iL y V W \ 



Upon the moulding lloor b there is erected a series of longitudinal partition plates c 
of length sufticicnt to accommodate any convenient number, and between these are 
inserted transverse partitions d formed of a continuous scries of short division plates 
inserted between the longitudinal partitions c, the whole being retained in position 
by the bottom pallets which correspond in length with the plates c. 

Running longitudinally of the compartments along the bottom angles are inserted 
filling blocks /, /^ faced with a veneer g, g^ of rubber, and in the upper corners of 

255 



RECENT BRITISH PATENTS. 



[CONCRETE] 



the compartments similar filling blocks /-, /*, faced in the same manner at g^, g', 
are also inserted, the filling blocks being attached to the partitions c. 

To form the cavities in the blocks, central cores h and additional cores i above 
and below the central cores are carried upon suitable supports, the cores being all 
formed of rubber tubes supported upon wooden or metal hkIs j, h, and / or upon 
helical spring members ni or n. 

As soon as the concrete mixture has been filled into the moulds and the initial set 
has occurred, the filling members such as j, k, I, m or n may be immediately with- 
drawn and the partition plates removed from all accessible portions of the collection 
of blocks. 

The exterior blocks are then easily taken away by manipulation of the bottom 
pallets or members e, and as soon as a block is separated and in a sufficiently dried 
condition, the corner filling blocks/, /^,/* and/', together with the central and smaller 
rubber cores h and i may be withdrawn, each block remaining upon its supporting 
bottom member e until it is sufficiently matured for handling and stacking. 

Fig. 5 shows the application of the invention to the formation of hollow concrete 
walls. In this case the rubber cores t or ii are made in lengths sufficient for a day's 
operations and are supported upon suitable hollow filling members v, zv, which may be 
positioned from rods x engaging cross pieces v at the ends of the fillings. Where 
a rigid filling is employed, these may be drawn upwards upon the rod while the con- 
crete is still wet without difficulty, the rubber being left for removal at a later stage, 
or the rubber may be supported upon helical filling which may be withdrawn in the 
most convenient manner. 

Concrete Wall Ties. — No. 151,755. Alexander Hardie, Ashgrove, Bo'ness, Lin- 
lithgowshire. Accepted October 7/20. — The present invention consists in a wall tie 
composed of water-proofed cement or concrete provided with a metallic core for 
reinforcement / and dovetailed at each end for engagement with counterpart pockets 
in the walls to be tied, the neck of the tie being formed with a ridge 2 for preventing 
the flow of water along the outer surface. 

In practice the dovetailed ends are dipped in bituminous material prior to their 
insertion into the pockets. 




Concrete Columns. — No. 151,765. Alexander Hardie, Ashgrove, Bo'ness, Lin- 
lithgoivshire. Accepted October 7/20. — This invention consists in an improved column 
comprising a superposed series of one-piece hollow concrete blocks i, the bore of each 
of which is formed with longitudinal dovetail grooves 2, the grooves being uninter- 
rupted from end to end and a core of concrete agglomerate inserted into the bore 
in fluid state, the arrangement being such that the core, when solidified, is in dove- 
tail relation with the blocks whereby the blocks are securely bound together. 

236 



n 



CONSTDUCTIONAL 
ENGTNIXKING — ; 



RECENT BRITISH PATENTS. 



Metallic rods 4 may be inserted into the core as shown for reinforcement, and 
rods 5 may also be inserted into the blocks. 

A 





Fig 1. 



Fia.2. 



Metal Forms for Concrete Cottages. — Xo. 152,130. Edward Dillon O'Grady 
Clarke, 33 Courtfield Gardens, South Kensington, London. Accepted October 11/20. — 
This invention comprises an improved mould made up of several steel sheets con- 
nected together, during the construction of the concrete wall and the like in situ, 
by means of the special hinge attachments. 

The mould is built up of vertically disposed and adjoining plates i and 2, which 




J^/ff.-2. 



t4- 






H 



6- 



--^ 



/J 



constitute the front wall plates of the mould, and Vertically disposed and adjoining 
plates 3, 4, and 5, 6 arranged at right angles to one another, which constitute the 
inner wall plates of said mould. The outer wall plates i and 2 are connected 

257 



RECENT BRITISH PATENTS. 



ICQNCBETEJ 



together, in a vertical direction, by a series of hinge attachments i6, whilst the inner 
wall plates 3 and 6 are connected to the inner wall plates 4 and 5, and at rigiit angles 
thereto, by a series of pairs of angle attachments 17. The members oi each pair of 
attachments 17 being arranged on the wall plates 3 and 6, and 4 and 5, respectively, 
the above described arrangement of plates giving, as shown in full lines, a T-shaped 
three-way mould for a solid wall. 

These outer and inner plates j to 6 are, at the sides remote from the before- 
mentioned hinge and the angle attachments, provided with a series of horizontal and 
longitudinally extending slotted bars or stretchers 15 riveted thereto, by means of 
which, and bolts 18 passed through the slots in oppositely disposed stretchers, 
additional outer and inner wall plates can be adjustably secured to the mould. 

To form a cavity wall, use is made of an inner mould, which mould is consti- 
tuted by vertically disposed and adjoining outer plates 7 and 8, and vertically dis- 
posed adjoining inner plates 9, 10, and 11, 12, the plates 10 and 11 being arranged 
at right angles to the plates 9 and 12, giving a T-shaped or three-way inner mould ; 
and the ends of said three-way inner mould are closed and sided with wooden blocks 
13 to form key-ways in the concrete wall, these blocks 13 butting against other 
wooden blocks 14, which blocks 14 serve as distance pieces to and between the ends 
of the plates forming the Outer mould. 

Pre-cast Concrete Floor Beams. — A'o. 152,160. IT. /. Stcn'cirt and J . Woolcock, 
12 Berkeley Street, IF.i. Dated August 12/19. — According to this invention pre-cast 
beam members of insufficient length to bridge completely the distance between the 
supporting abutments are arranged side by side with alternate members supported upon 
opposite abutments by one of tlieir ends, each meriiber being adapted to support the 





free end of the next adjacent or subsequently positioned member and the whole being 
incorporated into the floor by grouting and in situ work extending from the free ends 
to the adjacent abutments. 

The beams are preferably tapered and are constructed of a length which will not 
exceed the shortest span upon which it is desired to employ them as shown in Fig. 
7, and they are preferably of a length which is about 20 per cent, less than the span 
over which they will generally be employed, the structure for which they are required 
being as far as possible so designed that one length of beam will be sufficient for 
covering all the floors of the structure with varying lengths of in situ extension. 

Along the bottom edges the beams are provided upon one side with a projecting 
parallel ledge d, preferably reinforced as shown, and the other side of the beam which 
may be called the inner side is provided with a complementary recess e adapted to 
accommodate a projecting part of the ledge^^upon the outer surfaceof the adjacent beam. 

The beams in addition to the ledges are also provided upon their outer sides 
with a series of projecting contacting surfaces / along the upper edge of the beam, 
projecting about one half of an inch above the surface of the remainder of the side, 
so that when the inner side of one beam is pushed as close as possible against the 



258 



i 



CONSTRUCT!' 
EMOTNEERING 



IONALJ 
SG-— J 



RECENT BRITISH PATENTS. 



outer side of the next, there is provided a series of connected grout-spaces reaching 
from the top of the ledge to the top of the beam. 

At the wide ends which rest upon the walls or other abutments, the ledges d are 
strengthened by webs g, and the beams are made in pairs, that is right hand and 
left hand. 

Building Blocks for Cavity Walls.— A'o. 152,405- James Carter, Institute Build- 
ings, Windermere, Westmorland, and William Bennet, College Road, Windermere, 
Westmorland. Accepted October 11/20.— The improved building blocks constructed in 
accordance with this invention are characterised in that the interior face has a panelled 
surface with a longitudinal mid-rib, and cross ribs at right angles thereto, the recesses 
between the ribs having a plane surface, and in that the ends of the ribs at the edges 
of the blocks are left exposed, so that such ribs when the blocks are set up shall find 
their exact partners and be co-extensive with the ribs on adjacent blocks, whereby 
the accurate setting of the blocks by a sense of touch is facilitated. In a modifica- 
tion, the cross ribs instead of being at right angles to the longitudinal one, may be 
arranged diagonallv with respect thereto and arranged to cross one another, the 
diagonal ribs being likewise left exposed at the ends, so that when the blocks are set 
up, such ribs shall find their exact partners and be co-extensive with the ribs on 
adjacent blocks for the purpose of facilitating an accurate setting by a sense of touch. 

The blocks are moulded so as to have a plane front surface A A'^ and a recessed 
or panelled rear surface B. This recessed surface B is made with horizontal or cross 
ribs C, and the hollows or recesses B between the ribs have plane bottoms, such ribs 




and recesses being adapted to register with similar ribs and recesses in adjacent bricks 
or blocks, so that a wall built up of these bricks or blocks will present on one face a 
plurality of ribs C, D crossing each other at right angles with rectangular recesses B 
between the ribs, the depth of the recesses being about half the thickness of each 

block. 

Fig. 3 shows the blocks arranged with a jamb or rebate facing inwardly, so that a 
wood window frame G can be applied from the inside ; and 7-'/^. 4 shows the blocks 
arranged witli a jamb or rebate H facing outwardly, so that the wood window frame 
H can be applied from the outside of the wall. 

259 



RECENT BRITISH PATENTS. 



[CONO^ETEJ 



Concrete Block Walls. -A-'o. 152,776. Charles Marques, ir Osburne Road, 
Forest Gate, E.-j. Accepted October 22/20. — According to this invention a rein- 
forced concrete wall of the block type is provided with means for holding up at any 
required level a mass of new concrete or wall filling to form beams or girdering within 
the face of the wall. 




The structure is made up of oppositely opposed blocks a, a formed with one or 
more vertical webs b, b having reinforcements d, d between the blocks a, a. 

The horizontal reinforcements d, d extend along the length 

of the wall and lie in grooves e, e formed across the webs b, b of 

the blocks a, a. f, f are metal plates adapted to bridge the spaces 

between two oppositely opposed blocks and hold up concrete 

' about the horizontal reinforcements d, d. 

The plates need not be dished as illustrated but may be flat, 

* and in the latter case no grooves would be formed in the webs 
b, b, the reinforcements d, d simply resting on the said webs. 

In a modified construction each block is formed with an 
inwardly projecting ledge or shelf arranged that when the oppo- 

* sitely opposed blocks are placed in position the ledges abut against 
" one another and form a bed for the concrete. 

Concrete Framework Buildings. — No. 152, 888. William 

Emanuel Hale and Leslie Hugh Hale, 63 Belvidere Road, Wal- 

^ laser, Cheshire. Accepted October 28/20. — According to this invention 

a framework is provided comprising a plurality of precast concrete 

vertical units which engage precast inner and outer wall or like 

slabs in such manner as to leave a cavity between, while the 

parts are secured by grouting across the ends of the cavities 

Ts^^ adjacent to the framework units. The framework and slab units 

5' |-j are so shaped that they can be keyed together by a grouting 

applied in this manner. It will be seen that these units are not of 

the " block " type, as the vertical units are rather of the nature 

of pillars. 




260 



E 



CONSTKUCTlONALl 
ENGTNEERING — J 



RECENT BRITISH PATENTS. 



The framework vertical units consist of precast concrete pillars 1 having parallel 
inner and outer sides 2 and 3, but the lateral sides are shaped so as to key with 
the grouting, preferably by forming said lateral sides as two surfaces 4 and 5 with a 
re-entrant angle in the middle. Each side thus slopes inwardly from say the front 
edge and then half-way across slopes outwardly towards the back edge. 

The wall slabs 6 are correspondingly shaped at their ends, e.g. so as to slope 
outwardly when proceeding inwards from the edge. The inner face of the slab (next 
the wall cavity) is cut away for a short distance and situ concrete or cement grouting 
7 is then employed at this point (e.g. with the aid of temporary shuttering) to key 
the ends of the slabs to the lateral undercut faces of the foundation members. 

The framework may be reinforced by round steel bars 8 with suitable links 9 or 
wire binding and reinforcing bars 10 may be passed transversely through the pillars 
and their ends bent at right angles so that the bent ends 11 lie within the grouting. 
In some cases the lateral faces may be roughened or corrugated to ensure better 
adhesion. 

Ties for Hollow Concrete Walls. — No. 153,102. Thomas Arthur Locan, 323 
High Holboni, and David Eustace Landale, 34 Fenchurch Street, London. Accepted 
November 2/20. — This invention relates to concrete slab or block structures of the 
hollow walled type, wherein the walls are maintained parallel and at the proper dis- 
tance apart by means of U-shaped distance-pieces having parallel limbs bearing 
against the inner, opposed faces of the walls. 



rial 




The object of this invention is to provide improved means for tying together the 
walls of a concrete slab or block structure, and consists in providing such a structure 
with U-shaped distance pieces each combined with a tie member; one end of each 
engages in a concrete block or slab of one of the walls, while the other end of tlie 
tie member is extended through the opposite wall to engage with an outer shield or 
shield of reinforced concrete or the like, so applied as to become an integral part of 
the wall. 

The slabs or blocks of concrete are built up in a series of courses in the ordinary 
way so as to form inner and outer walls. Tlie devices b for maintaining the two walls 
parallel and at the proper distance apart, comprise the U-shaped strip c secured to 
the horizontal bar d projecting, on either side of tlie U-shaped strip c, one of the 



26X 



RECENT BRITISH PATENTS. 



[g3NCBETEJ 



projecting ends being bent downwards as indicated at a so as to form a iiook, whilst 
the other end is formed as a claw /. d^ are nail holes in the bar d. 

As the courses of the blocks or slabs are built up in two walls, the connecting 
devices b are applied so that the bars d rest upon the blocks and the legs of the Li- 
shaped strips c bear against the inner faces of the opposing courses of blocks, thus 
determining the distance apart at which the two walls are built and the parallelism 
of the two walls. The down-turned end e of each bar d is driven into the upper face 
of the blocks or slabs supporting them as indicated in Fig. i, and the other claw-like 
end of the strip projects beyond the outer faces of the (juter wall and is designed to 
engage the upright rods g around which they can be clinched, the bar d being nailed 
to the two walls by nails driven through the holes d^. 

Concrete Glazing Bars. — No. 153,800. Charles Edward Winter, 19 Harlescott 
Road, Waverley Park, London, S.E.18. Accepted November 18/20. — Astragals, glazing 
bars and the like constructed in accordance with this invention comprise in com- 
bination a sheath of sheet material, a reinforced concrete filling, and one or more 
longitudinal water-channels. 

The beam comprises an outer metal sheath a, Fig. i, provided with a reinforced 
concrete filling b which completely occupies the hollow interior of the sheath. 










lip^.'o 



<^:^ 




The compression area of the beam in question is augmented by increasing the 
width of the upper part of the beam beyond the limits set by the water channels d, 
an advantage not easy to provide in ordinary glazing bars owing to the difficulty 
of withdrawing the bar from the mould. Further, compression rods in the upper 
part of the beam may be dispensed with, as the sheath a provides sufficient strength 
in substitution. 

In the modification shown in Fig. 2 the wings of the sheath are terminated just 
bevond the water channels, and the glazing bar is completed by an uncovered base 
portion. 

Preferably, in both modifications, the sides of the base portion are tapered 
slightly to permit of easy withdrawal from the mould or holder. 

The sheath is preferably formed of non-corroding sheet metal, but iron may 
be used if desired, the exterior being suitably covered with paint. 



Seaham Harbour Concrete Road. — An experimental length of concrete road is 
to be laid down by the Seaham Harbour, Durham Urban District Council. The 
surv^eyor, Mr. F. E. Boaz, has been instructed to do the work immediately above 
Seaham Colliery Station. 

Reinforced Concrete Roadwork in Middlesbrough.— ^liddlesbrough Tramways 
Committee have accepted the tender of Messrs. Coxhead & Co., Middlesbrough, at 
;^6,837, for paving Grange Road in reinforced concrete. 



262 



f |J, CONSlBUCTlONAlJ 



CONCRETE RAILWAY WAGONS. 

CONCRETE RAILWAY WAGONS, 

The following particulars and illustraiions have been reproduced from " Belon u. 
Eisen." — Ed. 

The exceptional scarcity of iron and timber in Hungary has led to the construction 
of railway wagons in reinforced concrete and these have met with considerable 

success. 

The authorities concerned laid down the following conditions, which were all 

complied with : — 




The Austrian Ke Type. 




The Wagon after removal of Shuttering. 

(i) The concrete wagons must be of the same size and shape as the wagons 
ordinarily in use. 

(ii) Any interchangeable parts must be completely interchangeable, this 
condition to apply to wheels, hauling gear, buffers and couplings. 

(iii) The minimum weight of iron to be used with a maximum load-carrying 
capacity, but the weight per axle must not exceed 15 tons nor the total weight 
when loaded 30 tons. 

As built, each wagon has all the fittings of the standard Kmn Coal-trucks 
(without brakes) of the Hungarian State Railwa\'. The side walls have the same 
resistance to pressure as these standard wagons. The under frame consists of 

263 



CONCRETE RAILWAY WAGONS. 



[CQNCBETEl 



two outer and two inner longitudinal girders, two cross girders at front and back 
and a number of sui)plemcntary ties. All these are arranged to form a mono- 
lithic structure. 

The front and back openings of reinforced concrete are replaceable and the 
side openings, edges, sills and lintels are all protected by angle iron. The various 




Front View of Kmn Type. 




A Concrete Oil Tank. 



metallic parts are screwed into the concrete, the female parts of the screws being 
cast in the concrete. The concrete for the under carriage was composed of 
I part of cement, i part of gravel, and 2 parts of sand ; that for the sides of i 
part of cement, 2 parts of gravel, and 2 parts of sand. The iron rods used for 
the reinforcement were 0"i6-072 in. diameter. 

Each wagon weighed ii| tons when empty and i8| tons when filled with 

264 



[&^igg^j^^ CONCRETE RAILWAY WAGONS. 

coal, but if a highly porous aggregate were used the tare of the wagon could be 
reduced to 9 tons. As the specific gravity of concrete is four or five times that 
of wood, it seems inevitable that concrete wagons should be heavier than tho?e 
made of timber. The advantage of concrete lies in the much smaller quantity 
of iron required and in the complete saving of timber at a time when iron and 
timber are both scarce. 

A wagon of a slightly different type — being the standard Austrian {Ke) 
type and about 3 ft. longer than the Hungarian ones — was built by W. Custer 
at the Simmeringer Wagon Works, Vienna. This wagon was made to resemble 
the standard trucks as closely as possible, but the mode of fastening the wheel 
brackets to the under carriage, the fastening of the couplings and the arrange- 
ments for reducing damage in the event of a collision are different. A door at 
one end is larger than in the Hungarian truck and the ironwork extends to the 
top. The Austrian wagon weighs about a ton more than the Hungarian one, 
but in future designs a reduction of weight will be made. 

Three tank-trucks of 518, 666 and 925 cubic feet capacity were designed to 
be built of reinforced concrete. Such wagons require much more skill in design 
and construction as a small crack, which would be negligible in a coal-truck, 
would be very serious in an oil-tank, and eventually two tank-trucks, each of 
925 cubic feet capacity, were built. It is too early to report adequately upon 
their durability, but up to the time of writing they are quite satisfactory. 

THE MACQUARIE BRIDGE [continued from page 222). 

The main trusses are 22 ft. deep between centres of chords and are spaced 23 ft. 
6 in. apart centre to centre. The panel length of 12 ft. was fixed as being the 
greatest span which would permit of a rolled girder 24 ft. by 7I in. by 100 lb. per 
foot run being used as a cross girder. 

The deck slab is 6^ in. thick with a concrete wearing surface 2\ in. thick at 
the centre and ^ in. at sides reinforced with round bars. 

The deck on the reinforced concrete beam spans is 9 in. thick with a covering 
of tarred metal. The beams are 2 ft. wide and the depth from the top of the slab 
to the underside of girder is 3 ft. The beam reinforcement consists of twelve i| in. 
diameter rods bent up at various points to resist the shearing stresses which are 
also further provided for by vertical stirrups. 

The bridge was designed for a live load of 100 lb. per square foot uniformly 
distributed for the carriage and footway and for a 24-ton lorry road, the weights 
on the rear axle being taken as 16 tons ; the wheel base assumed for the lorry was 
12 ft. by 6 ft. The trusses were further designed for a moving load of 9 tons per 
panel at such points as to give a maximum stress in any member. 

The work was divided up into three contracts. Contracts No. i and 3 were 
carried out by the State Monier Pipe and Reinforced Concrete Works, and No. 2 
by the Government Dockyards at Walsh Island, Newcastle, at a total cost of 
£23,326. 

The structure was designed by the officers of the Public Works Department 
under Mr. R. E. Jones, M.Inst.C.E., whilst the work of construction was carried 
out under the supervision of Mr. Morrice, District Supervising Engineer, acting 
under Mr. Percy Allan, M.Inst.C.E., M.Am.Soc.C.E., Chief Engineer for National 
and Local Government Department. 

F 265 



OSCAR FAttER. 



ICONCBETliJ 



CONCRETE IN THEORY 
AND PRACTICE. 

A practical section especially written for the assistance of studeiits 
and engineers, and others who are taking up the study of reinforced con- 
Crete, or who are interested in the subject on its educative side. 

REINFORCED CONCRETE SIMPLY EXPLAINED. 

By OSCAR FABER, O.B.E., D.Sc, etc. 

In this series of articles it is proposed to keep explanations so simple as to be 
intelligible to anyone desiring to understand the underlying principles of reinforced 
concrete withmU wading through a lot of mathematics. The results will be accurate 
and will agree with L.C.C. regulations, but unit be more easy to understand. The 
articles should also form an excellent introduction to those who will need to follow 
them up with a more advanced work. — Kd. 



CHAPTER VI. 
Materials. 

73. Having now discussed the general 
theory of design as far as is possible in a 
simple description as opposed to a special- 
ist's treatise, we are in a position to 
describe more carefully and intelligently 
the materials used and some of the pro- 
perties of the concrete. 

We will first consider the materials. 

Concrete. 

74. Voids. Concrete is to be considered 
as a mass of stones having certain spaces 
or voids between them. 

These voids are then filled with sand, 
which in turn contains voids. 

The voids in sand are not so obvious as 
those between the stones, but in fact there 
is often about the same proportion of 
voids in sand as in the stone. 

The voids in the sand are finally to be 
filled with cement for the mixture or 
concrete to be quite solid and dense. 

Suppose, for example, the stones 
contain 40 per cent, voids, then if the 
sand could be inserted between them 
without separating them, obviously the 
sand volume should be 40 per cent, of 
the stone volume (both volumes being 
measured to include solid and void in 
natural proportion). In practice, it is 
impossible to get the sand to fill the stone 
voids without some sand particles also 
remaining between the stones where they 
would otherwise touch, and generally it 
is necessary to add about 10 per cent, 
(depending on size of particles chiefly) 
more than the void contents. 

Thus a stone with 40 per cent, void 
needs in practice 40 per cent. + 10 per 
cent. = 50 per cent. sand. 

The same applies to the sand voids. If 



the sand contains 30 per cent, voids, then 
if the cement could be made to fill the 
voids without separating the sand particles, 
30 per cent, of the sand volume should be 
the cement contents. In practice, a 
greater volume is required, because the 
cement, besides filling the voids, also 
forms an adhesive film round the surface 
of sand and stone particles, and in practice 
about 20 per cent, more cement is re- 
quired, so that roughly 30 per cent. + 
20 per cent. = 50 per cent, of the sand = 
cement required. 

It will be seen that if the stone needs 
50 per cent, sand, and the sand needs 50 
per cent, cement to fill all the voids, then 
a concrete of 4 parts stone, 2 parts sand, 
I part cement practically meets the re- 
quirements of a dense solid concrete. 

If the stone contains less voids, less sand 
and cement is needed, and if the sand con- 
tains less voids, less cement is needed, 
and the correct proportions can easily 
be estimated when the voids are known. 
In practice, the voids are easily deter- 
mined by the simple process of weigh- 
ing a given volume of sand or stone. 
It may be taken that the solid material in 
nearly all common stones weighs almost 
exactly 160 lb. a cu. ft. If, therefore, a 
sample of broken stone including voids 
weighs only 106 lb., the solid material 

will be — = 60% and the voids 100 — 60 = 
160 

40%. 

It will be found in practice that angular 
stone has a higher void percentage than 
rounded stones, and therefore needs more 
mortar (sand plus cement) to fill its voids. 

When the voids are not completely 
filled the concrete is known as hungry. 
Not only is the strength impaired, but the 
waterproof properties, and the protection 



266 



r ir OONSTRUCTlOT<iALl 



CONCRETE IN THEORY AND PRACTICE. 



of the reinforcement from corrosion is also 
seriously reduced. 

When measuring the void contents m 
sand certain interesting facts exist which 
bear on the problem. 

If a box containing dry sand has water 
poured on it, the sand will settle so that 
it no longer fills the box. If it is then 
tipped out, it will be found to be more 
than is required to fill the box. In the 
first case, the effect of water was to reduce 
the friction between the particles and 
cause them to settle down closely together, 
while in the last case, where the water is 
not actually poured on, but only the 
water adhering to the surface is left, the 
surface tension prevents movement of 
the particles, just as wet sand will make 
a castle at the sea-side while dry sand 
refuses to stand. 

For the purpose of measuring the voids, 
the densest condition should be chosen, 
because in ordinary concrete there is 
enough water to allow of free movement of 
the particles. 

A good and ready test of the success 
attending the proportioning of concrete 
is clearly the weight of a cube of concrete, 
since the difference between the weight 
of concrete per cubic feet and i6o lb. 
indicates the amount of voids left unfilled. 
This test applies to cubes made of granite 
ballast, quartz, shingle and sand, etc. In 
the case of broken brick of a porous 
nature, it is of course impossible to make 
so heavy a concrete, as the voids in the 
brick itself cannot readily be filled. 

With dense materials, a cube often 
weighs 146 lb. a cubic foot, indicating 
about 10 per cent, voids in the finished 
concrete. Many experiments have clearly 
demonstrated that the heavier cube is 
also the stronger, and the reason should 
be obvious from what has been said. 

It is impossible at present to make a 
concrete entirely without voids, because 
when the concrete is mixed with water in 
the mixing, this water represents a 
considerable volume. Altliough part of 
this water enters into chemical com- 
bination with the cement, the larger part 
does not, but subsecjuently evaporates 
and is replaced by air. It becomes clear 
from this that an excess of water in 
concrete reduces the strength because 
the concrete will be less dense. This is 
well imderstood by cement-testers who 
will spend time in ascertaining for any 
sample of cement the minimum pro- 



portion of water which can be used, and 
will often secure tests exceeding by 20 
per cent, those made with a more hberal 
supply of water. 

Excess of water has other disadvantages 
which will be referred to later. 

75. Cement Contents. From the above 
it might be concluded that if the pro- 
portions have been so adjusted as to fill the 
voids in the manner indicated no advan- 
tage accrues from adding more cement. 

This, however, is not so, as the follow- 
ing table of representative tests indicates. 





Sand. 


Stone. 


Crushing Strength. 


Cement. 






2 




I month. 


4 months. 


I 


4 


1,500 


2,250 


I"2 


2 


4 


1,650 


2,475 


I'S 


2 


4 


1,800 


2,700 


2 


2 


4 


1,950 


2,925 


neat cement. 


5,000 


7,500 



Tliese tests being of cylinders in prefer- 
ence to cubes for reasons to be stated 
later. 

The reason why a greater cement 
content increases the strength of concrete, 
even when this is tested in compression, 
and even after all the voids seem to be 
filled as far as practicable lies in the nature 
of failure of a concrete cube in crushing. 

As a rule the crushing takes place by 
the wedge-like action of the stones 
sphtting the block laterally, dividing it up 
by vertical lines into several prisms 
liable to buckle. This action is resisted 
by the tensile strength of the concrete. 

"Now the tensile strength across any 
concrete fracture consists partly of the 
adhesion of cement to stone particles in 
the section, and partly by the tensile 
strength of cement to cement in the 
interstices between the stones. The 
greater the cement contents, the greater 
proportion of area at any section is 
cement and not stone, and therefore the 
greater the tensile strength. 

.\s has just been mentioned, the crush- 
ing strength is really limited by the 
tensile strength, and therefore it happens 
that there is an almost constant ratio 
between the compressive and tensile 
strength of all brittle materials, of which 
concrete is one. In the case of concrete 
this ratio is about ten to one. and if the 
table given above is divided by ten, it 
gives average values of tensile strengths, 

267 



OBITUARY. [Cr^vlCRETE] 



I L 



©bituav^. 

THE LATE FRANCOIS HENNEBIQUE. 

We deeply regret to liave to announce the death of M. l-'rancois Henne- 
bique of Paris, which took place last month. As is well known to our 
readers, Francois Hennebique was one of the world's pioneers in rein- 
forced concrete, and it was his studies and investigations which have 
given to the world the special form of construction known as Ferro-Concrete, 
a system which lie had worked out in all its details in order to make it 
applicable to any kind of construction. The special features of his system 
have been frequently illustrated in these pages, and readers are familiar 
with many of the structures erected under it. 




Francois Hennebique was born at Neuville St. Waast (Pas de Calais) 
in 1842, and early in life he developed a special bent for the mechanical 
arts. After years of close theoretical study and practical work he estab- 
lished himself as a contractor for public works, and soon found himself 
entrusted with every kind of construction, large public buildings, bridges, 
viaducts, etc . His early studies in stereotomy and architecture also enabled 
him to apply his special knowledge to the restoration of a number of historic 
monuments, among them the churches of Notre Dame and St. Courtrai. 

In spite of his numerous activities he found time to study concrete 
and its effects in combination with rods of steel or iron. It was only 
after exhaustive study and investigation that he hnally made his system 
known to the public in 1892, from which time onwards it has developed 
to such an extent that it is now known and used in all parts of the world. 



268 



r V, CONSTBUCnCSMAlJ 
[t\ ENGiytXRlNG — -J 



CEMENT NOTES. 



CEMENT NOTES. 

By Our Special Contributor. 



Calcium-Aluminate Cements. 

In the January issue of this Journal, the 
suggestion was made in these Notes that 
rapidity of hardening would be one of 
the directions in which the cement of the 
future might be an improvement upon 
the current material. A remarkable 
development in this direction is now 
revealed in some tests made by the U.S. 
Bureau of Standards with calcium- 
aluminate cements. The main con- 
stituents of these cements are lime and 
alumina chemically combined, although 
silica up to lo per cent, and iron oxide up 
to 3 per cent, may apparently be present 
without disadvantage. Calcium-alumin- 
ate cements differ from Portland Cements 
in containing alumina as the second 
predominating constituent instead of 
silica. 

Crushing strengths of 3,000 lb. per 
sq. in. in 24 hours have been obtained 
from a concrete containing i part calcium- 
aluminate cement to 6 parts aggregate, 
this being more than the strength expected 
from a Portland Cement concrete at 
28 days. Similarly a 1:3:9 gravel 
concrete with calcium-aluminate cement 
gave a result of 3,415 lb. at 28 days 
and 4,445 lb. at i year. 

These are startling results and subject 
to possessing the necessary qualities of 
stability and resistance to atmospheric 
conditions, the calcium-aluminate cements 
may have an important bearing upon 
the constructional work of the future. 

It should be understood that these re- 
sults are the results of laboratory experi- 
ments, and the manufacture of calcium- 
aluminate cements has apparently 
not yet been attempted on a practical 
scale. Hitherto, cements with unusually 
high proportions of alumina have been 
regarded as suspect, especially for use 
under marine conditions, and it may be 
that calcium-aluminate cements will not 
stand the test of practical use. In the 
present stage, therefore, the tests re- 
ported are more of interest to the researcii 
worker than to the engineer, although 
they may suggest to the latter possibili- 
ties in connection with concrete which 
have previously been rejected as idle 
dreams. 



Concrete Improvers. 

There are differences of opinion as to 
the necessity or desirability of using any 
waterproofing agents with concrete. The 
view taken by cement manufacturers 
generally is that a good cement in the 
right proportion with a well-graded 
clean aggregate will yield a water-tight 
concrete, and the opinion of the manufac- 
turer in this connection should carry 
much weight. 

So far as is known the most authorita- 
tive pronouncement upon the subject is 
that by the American Bureau of Standards 
after an examination of forty water- 
proofing compounds. The report states : 
' ■ Portland cement mortar and concrete 
may be made practically water-tight or 
impermeable ... to any hydrostatic 
head up to 40 feet, without the use of any 
of the so-called ' integral ' water-proofing 
materials, but in order to obtain such 
impermeable mortar or concrete, con- 
siderable care should be exercised in 
selecting good materials as aggregate 
and proportioning them in such a manner 
as to obtain a dense mixture. 

" The addition of so-called ' integral ' 
water-proofing compounds will not com- 
pensate for lean mixtures, nor for poor 
materials, nor for poor workmanship 
in the fabrication of concrete. Since in 
practice the inert integral compounds 
(acting simply as void filling material) 
are added in such small quantities, they 
have very little or no effect on the per- 
meability of the concrete. If the same 
care is taken in making the concrete 
impermeable without the addition of 
water-proofing materials as is ordinarily 
taken when waterproofing materials are 
added, an impermeable concrete can be 
obtained." 

The object of this note is, however, not 
to discuss the merits of the water- 
proofing compounds on the market, but 
to call attention to what is considered a 
legitimate concrete " improver," viz. 
silicate of soda. This material is other- 
wise known as " water glass " and is 
retailed as a viscous hquid for egg 
preserving ; it is not a proprietary article. 
Silicate of soda is fundamentally sound 
as an improver of concrete because it 

269 



CEMENT NOTES. 



E^scmLitJ 



provides active silica which can combine 
with hme set free during the setting 
process of cement and thus form sihcate 
of hme, which is one of the compounds 
contributing to the strength of cement. 
A convenient sohition to use is obtained 
by mixing i lb. of silicate of soda with 
I gallon of water, and the solution can be 
applied with a watering-can fitted with 
a rose, or with a whitewash brush. 
Three applications at intervals of about 
two days usually yield the best result, 
but it should be understood that the 
treatment is essentially a surface treat- 
ment only and only efficacious in so far 
as the solution penetrates the -concrete. 
The following tests for tensile strength 
of briquettes of i sq. in. in section 
immersed in a solution of sodium silicate 
show the increased strength resulting 
from the treatment : — 

7 days neat immersed 

in water . . . 590 lb. per sq. in. 

7 days neat immersed 

in sodium silicate . 670 ,, ,, ,, ,, 

7 days (3 sand, i ce- 
ment) in water . 267 ,, ,, ,, ,, 

7 days {3 sand, i ce- 
ment) in sodium 
silicate .... 382 ,, ,, ,, ,, 

As a surface hardener, silicate of soda is 
especially useful for the treatment of 
concrete floors to increase the resistance 
to wear and to enable traffic to be put on 
the floor at an earlier date than would 
otherwise be possible. 

It is impracticable to mix silicate of 
soda with the water used for mixing the 
concrete, because it acts to some extent 
like carbonate of soda in causing the 
cement to set very rapidly. 

Rough and Ready Tests for Cement. 

The need is often felt by Clerks of Works 
and Contractors' foremen for simple tests 
of cement which they could apply them- 
selves and so avoid the delay and expense 
associated with experts' tests. This need 
becomes particularly acute when a batch 
of concrete fails to harden or when a 
range of cement- jointed pipes does not 
stand the water test. In such cases, the 
user generally regards the cement as the 
unknown factor and is inclined to blame 
it, although if a simple test were avail- 
able, tiie responsibility could soon be 
placed in the right quarter. 

In spite of the absence of official tests 



of this naturjL', it is frequently observed 
that attempts are made to test the 
quality of cement without having recourse 
to an expert. The boltle test is one method 
adopted, consisting of filling a glass bottle 
or jar with cement paste and observing 
whether the cement on setting contracts 
and becomes loose, or expands and cracks 
the glass. This is quite unreliable as a 
test and must be unreservedly condemned. 
If the cement does become loose in the 
glass vessel, it is merely an indication 
that too much water has been mixed with 
the cement, while if the glass cracks the 
cause may possibly be expansion of the 
cement, but is far more Ukely to be the 
difference in the rate of expansion and 
contraction of glass and cement with 
changes of temperature. Many have had 
the experience of retaining for six months 
a dozen or more glass vessels filled with 
different cements and finding the whole 
of them cracked on one day owing to a 
sudden change in temperature. 

The immediate immersion test is another 
attempt at discovering the qualities of a 
cement in a few hours. This test con- 
sists in immersing a pat of cement paste 
in water immediately after mixing and ob- 
serving in twenty-four hours whether the 
pat is soft, cracked or deformed. All that 
need be said of this test is that it has been 
considered by the Engineering Standards 
Committee and expressly excluded as 
depending upon setting time more than 
any other factor. 

A third test, and the only one that is 
worthy of consideration, is that of mixing 
the cement with water and observing the 
setting and hardening. As frequently 
carried out, this test is misleading, and to 
provide useful information it must be 
conducted as follows : — 

About I lb. of cement is laid on a sheet 
of non-porous material (slate, glass, or 
iron, but not brick, tile, or wood) and 
mixed with just sufficient water to make 
a stiff paste. If the mixture is at all 
" sloppy " more cement should be added 
to stiffen it and care must be taken to 
get a thorough mixture of cement and 
water. The paste is then formed into a 
square or circular cake about an inch 
thick and put in a place where it will 
remain at an even temperature and out 
of the influence of draughts. A good 
plan is to cover the pat with an inverted 
box. The pat is then tested with the 



270 



&' coN5rBucna>4Aii 



finger-nail or pencil point every ten 
minutes for the first hour and thereafter 
every half-hour, to ascertain the progress 
of setting, while if it is kept a day or two 
a good idea will be obtained of the harden- 
ing qualities. It is essential that the test 
should be made in a building at a tem- 
perature of about 60° F. and the pat 
maintained within 5° of this temperature 
throughout, otherwise the result will be 
misleading. 

If when the pat is hard it is immersed 
in water and boiled for a few hours and 
then found to be free from any pro- 
nounced cracks or marking, it will be a 
reasonable conclusion that the cement is 
sound. 

This test, if conducted with care, 
should provide evidence of the setting and 
hardening qualities and soundness of a 
cement. If the results are not satisfac- 
tory to the user he should inform the 



NEW BOOKS. 

cement manufacturers or submit a sample 
to a recognised cement expert. 

A parallel test under similar conditions 
of a mixture of the cement and the aggre- 
gate to be used with it can also be made, 
and if the neat pat is good while the con- 
crete pat has failed to harden, there is 
evidence that the aggregate is faulty. If 
both pats are good and the concrete laid 
in practice is faulty, the indication is that 
in the latter case, workmanship or weather 
is responsible. 

It must be remembered that at the 
best these tests are " rough and ready " ; 
if they give satisfactory results there is 
evidence that the cement sets properly 
and is sound, but if the results are unsat- 
isfactory, it is not at all certain that the 
cement is inferior in quality, because even 
with such apparently simple tests as 
these it is easy for a novice to make 
mistakes which vitiate the results. 



NEW BOOKS 

AT HOME AND ABROAD. 

A short summary of some of the leading books which have appeared during 
the last few months. 



Engineering and Building Foundations. 
Vol. I. Ordinary Foundations. t>y 
Charles Evan Fowler, C.E., Consulting 
Civil Engineer. 

Chapman & Hall. Price 27s. 6d. net. 

This is quite one of the best books on 
the subject we have seen. Its contents 
include a very interesting historical 
development, after which the actual 
construction and practice of crib coffer 
dams, cribs and canvas, pile driving 
and sheet piles, sheeting piles, con- 
struction of sheeting piles, removing 
old piers, pumping and dredging, is 
followed by the construction of ordinary' 
foundations for all kinds of structures 
and on all kinds of conditions of the soil. 
Allocation and design of piers, calculation 
of piers, footings, and retaining walls, 
timber piers, and timber preservation, 
retaining walls and culverts, design of 
masonry abutments and masonry piers. 
The work is brimful of information — 
both on the theoretical and practical 
side, and is full of illustrations and 
examples taken from the best practice. 
The eleven appendices give the specifi- 
cations, or extracts from specifications 
of many interesting bridges, dams, coffer 
dams, metal sheet piling, floating pile 



driver. United States cement specifica- 
tion — Nav3'- Dept. — etc. Some idea of 
the information contained in this volume 
may be gathered from the fact of there 
being 286 excellent illustrations and 
49 tables. The work is also excellently 
laid out and indexed. We know of no 
volume which collects so much valuable 
information on the subject which it deals 
with as this volume, and we confidently 
recommend it to anyone whose pro- 
fessional work requires ready reference 
to what has already been told on this 
very important subject. Mr. E. L. 
Corthell's excellent monograph on the 
allowable pressure on deep foundations, 
which is a work of the highest importance, 
finds a place in precis form — as indeed 
it should in any reputable work on this 
subject. 

Concrete for House, Farm and Estate. 
(Second Edition.; By Fred Ballard. 

Crosby, Lockwood & Son. Price 3s. 6d. net. 

Nothing, perhaps, in the construc- 
tional methods of to-day is more striking 
than the large and ever-increasing variety 
of uses to which concrete is being applied 
in all directions, not merely as a substi- 
tute for other materials but as a struc- 
tural material in itself. One of the 

271 



QUESTIONS AND ANSWERS. 

reasons for this is to be found in tlie 
fuller appreciation of its valuable pro- 
perties and its superiority for many 
purposes over timber, brick, iron and 
steel. 

The numerous ways in which concrete 
can be employed on the estate and farm 
and for the erection of houses are described 
in a clear and interesting manner in a 
bright little book by Mr. Fred Ballard, 
obviously written by a practical man 
and addressed, not to the technologist, 
but to the ordinary reader. 

We heartily endorse the opinions 
expressed in the preface that " An ele- 
mentary knowledge of reinforced con- 
crete should form part of the education 
of an Architect and Builder," and that 
" A careful study of the material will be 
rewarded by efficiency and reduction in 
cost." Mr. Ballard makes a good point 
when he says that for years to come the 
demand for timber will exceed the supply 
and the price will be high, and " If the 
demand for timber were confined to 
woodwork essentials, timber, and even 
bricks, might be largely excluded from 
general construction work in buildings 
by substituting reinforced concrete." 

One of the advantages of concrete is 
that it is " composed of home material. 
Its all-round production and cost is 
mainly labour. With unskilled labour 
and a good foreman excellent results 
may be obtained." 

The author is evidently a firm believer 
in sound workmanship and wisely emplia- 
sises the importance of efficient mixing, 



KONCBETEJ 



since, as he states, badly mixed concrete 
will spoil well-designed work, and a 
badly mixed i to 4 may not be equal to 
a well-mixed i to 8. 

One fact, we think, is hardly brought 
out with sufficient clearness, and that is 
that I part of cement mixed with 2 
parts sand and 4 parts coarse material, 
all by volume, does not produce a mixture 
of I part cement to parts aggregate, 
since the greater part of the sand goes to 
fill the voids in the coarser aggregate. 
This is a point often lost sight of when 
proportioning. 

The value of concrete for the elimina- 
tion of the rat nuisance is strikingly 
illustrated, and the description of a rat- 
proof granary which has been in use for 
some vears is very instructive. 

The question of ensilage has never 
received in this country the considera- 
tion which it de.serves ; in America over 
half a million silos are in use. There is 
plenty of evidence, however, that British 
agriculturists are realising the value of 
this form of fodder and silos are now 
being erected all over the kingdom. It 
is interesting to learn that the first silo 
erected in Herefordshire was built in 
concrete on Mr. Ballard's farm, and his 
book very fittingly concludes with instruc- 
tions for the erection of silos in concrete, 
than which in his opinion there is no 
more suitable material. 

The book is written in very simple 
language, entireh' free from technicalities, 
and should appeal to a ver}' wide circle 
of readers. 



QUESTIONS AND ANSWERS 
RELATING TO CONCRETE. 

In response to a very general request we are re-starling our Questions and 
Answers page. Readers are cordially invited to send in any questions. These 
questions will be replied to by an expert, and, as far as possible, they will I?e 
answered at once direct and subsequently published in this column for the infor' 
rnation of our readers, where they are of sufficient general interest. Readers 
sho^ild supply full name and address, but only initials will be published. Stamped 
envelopes should be sent for replies. — Ed. 



Question. — /. B. S. ivrites : — Having 
studied the valuable and simple article in 
Concrete by Dr. Oscar Faber, will you 
be good enough to furnish me in a subse- 
quent issue 7vith a simple formula for 
Columns of ferro-concrete with eccentric 
load {say, for a travelling crane). Would 
you please also tell me if cantilevers are 
treated in exactly the same ivay as for 



beams, the only difference being the B.M. 

WL . ' " WL . 

= instead of —5- ir.e. B.M. = 

2 -' o 

M. R. 95 X b X d X d and the area of 



steel in the tension side A = 



•675 



X 



d X b. Is it safe to calculate a retaining 
wall as if it were a cantilever, provided the 
thrust is calculated for such a ivall and used 



272 



r 9- CONSTBUCnONAlJ 
l*^ EMGITrtXBlNG -~j 



QUESTIONS AND ANSWERS. 



as the distributed load? According to the 
two formulas {cantilevers and retaining 
walls by Mr. Faber) the results are exactly 
similar. 

Answer. — Columns with eccentric loads 
must be calculated for concentric loads 
and for the bending moment. When the 
bending moment is small this may be 
done in exactly the same way as the 
treatment in " Reinforced Concrete Sim- 
ply Explained " of last month's issue, 
where both the load and the bending 
moment on a certain column was given 
and the stress due to each calculated and 
added together. This formula is only 
strictly accurate in such cases where the 
eccentricity is so small that the stress 
due to bending is not greater than the 
stress due to the direct load. When the 
bending moment or eccentricity is 
appreciably greater, the method of cal- 
culation used in last month's article fails 
to be accurate because the moment of 
inertia of the column then becomes differ- 
ent owing to the concrete failing on the 
tension side. In this case there is no 
simple formula for calculation, and the 



easiest and most exact method is that 

given in Reinforced Concrete Design, Vol. 

I. 

Cantilevers are treated in exactly the 

same way as for beams, bending moment 

WL . 
bemg lor a distributed load, or 

W L if the whole load is concentrated at 

the end, but the tension steel in the case 

of a cantilever with a downward load 

should be placed at the top instead of at 

■675 
the bottom and may be 



moment 



b d when 
100 

is taken as 



the resistance 
^ = 95 b di. 

In reply to the last paragraph, a 
retaining wall is certainly a cantilever, 
provided the thrust and its point of appli- 
cation are correctly calculated. There 
are, however, several points about the 
design of the retaining wall which a 
knowledge of cantilevers does not suffice 
in solving — such as the distribution of 
pressure on the ground, the question of 
stability, and so on. Some of these 
questions are dealt with in Reinforced 
Concrete Design, Vol. I. 



MEMORANDA. 

Repairing Leaks in Concrete Water Tanks with Bran. — Two sub-surface concrete 
tanks whicli had been leaking badly were effectively sealed by the use of bran. The 
tanks in question measured 20 ft. in length by 10 ft. wide and 18 ft. in depth. The 
walls and floors were of reinforced concrete and were 10 in. thick at the top. Plas- 
tering of the inside faces of the tanks, which are built into the ground, proved to 
be of no use, as the water leaking from the outside washed the cement away as soon 
as it was applied ; therefore some other way of making the tanks watertight had to 
be devised. 

The following process was then tried with remarkable success. The tanks were 
filled with water, and the pressure being greater on the inside faces than the outside, 
the water ran cjut through the leaks to quite an extent. Ordinary bran was used as 
a sealing material. The surface of the water all around the walls for a width of about 
one foot, was covered with bran. This bran floats for some time until it takes a gluish 
form, when it starts to sink, but very slowly, and in going down, following the sides 
of the walls, the sticky substance is naturally drawn towards the holes into which 
it deposits itself, being forced in by the pressure of the head of water in the tank. 

The operation was repeated until the tanks were made absolutely watertight, 
riiey have ncjw been in use since November, IQ19, and have not leaked at all since. 
Canadian f''ns;in('er. 

Repairing Stone Arch Aqueduct with Cement Gun. — The Pennsylvania State 
Highway Department recently made interesting use of the cement gun in repairing 
a stone arch aqueduct. 

The stone arch was in very poor condition when tlie State took it over. The 
mortar joints had deteriorated so badly that some of the ring stones of the arches 
had fallen out. 

In repairing this aqueduct to meet the requirements of a modern highway bridge, 
the joints in the cut stone face were raked and repointed by hand. The joints in the 
s(jffits oi the arch rings were cleaned out and then shot full of mortar with a cement gun. 



^73 



NEW METHODS OF CONSTRUCTION. 



[CONCi^lU 




NEW METHODS 

OF 
CONSTRUCTION. 



f 




In recent issues we have given a list of new methods of construction which 
have been passed by the Ministry of Health in connection with hmising schemes, and 
so thai ovj readers may have fuller particulars of these methods, ve 7)ropose publish- 
ing some further infommaiion regarding same, based on details supplied to us 
by the different firms putting forward new methods. — Ed. 



A SIMPLIFIED CONCRETE CAVITY WALL. 

A NEW and simplified method of erecting concrete cavity walls has been devised by 
Messrs. Evans and Howarth. 

The main features, as detailed in the accompanying drawing, consist of a timber 
core piece (which forms the cavity) on the outside of which is placed sheet iron to 
prevent adhesion of the concrete mixture to the core piece. A ring bolt is placed 
in the centre of the timber and is fitted with a loose link through which an iron lever 
bar can be inserted to form leverage and facilitate removal of the core piece after 
the concrete has set. On either side of the ring bolt, hand grips are fitted, allowing 
the centre to be easily lifted out by hand, once the lever has released the pressure. 

The timber core piece is built of ordinary f-in. spruce boarding with battens in 
the centre of the graduated thickness, in order to give the whole a taper of ^-in . between 
the top and bottom, and both ends are boarded flush with the side. The covering 
consists of four pieces of light sheet iron, bent over at the ends and overlapping each 
other so as to prevent the cement from reaching the core piece. These pieces 
of sheet iron are held in position by wire bands. 

The cores are placed in position between the wood shuttering, and the concrete 
is poured around and allowed to set, after which the cores are released, and are then 
available for use in raising to a second position. 

Two small grooves are made in the base about, i J in. to allow the core piece to 
fit over the cavity ties placed in position on the set concrete, thus permitting the 
core piece to pass below the set concrete about i in., making the whole self-fixing and 
preventing any concrete from falhng down the cavity. 

The cavity ties act as a support for the core piece and prevent the iron sheets 
from falling down the cavity when the timber cores have been removed. 

This method can be adapted to the construction of chimney stacks and flues. 

The advantages claimed for this method of construction are : 

1. The whole of the work can be carried out by unskilled labour. 

2. The cost of plastering is considerably reduced as the walls will not require " ren- 
dering " with hair mortar, as skimming over only will be necessary. 

3. Window frames and doors are placed in position as the work proceeds, and 
secured by simple devices which entirely do away with the usual method of securing 
same by nailing. 

4. A saving of time is effected. 

Further information can be obtained from Messrs. Evans & Howarth, Contrac- 
tors, Whitefield Road, Liverpool. 



274 



I ». 0CM3TUUCT10NA lJ 
1<^C ENTjyjFFBlNG -^ 



NEW METHODS OF CONSTRUCTION. 




275 



MEMORANDA. 




1 



MEMORANDA. 






m^lMti 



Mcniordnd-a and .Veu-s Items are presented under this heading, with fxcattioruU 
((liloriul comment. Authentic news will be welcome. — Kd. 



Curiosities near Salisbury. — ^The accompanying illustrations show interesting 
and unusual uses of concrete, both of which are to be found at Lake, near Salisbury. 
Fig. 1 is a single storey dwelling that was built about fifty years ago, to house a loom 
at the time when an effort was being made to revive village handicrafts. On a plinth 
of brickwork a timber framing was fixed and to this framing boards were nailed which 
formed a shuttering, the boards were subsequently removed but the timber frame 

remained. The wall is thus 
solid concrete panels enclosed 
by timber uprights cill and 
plate. The fall of the ground 
enabled cellars to be con- 
structed. The attempt at 
reviving the hand-loom not 
proving a success, the build- 
ing was used as a dwelling, 
which purpose it still fulfils 
with entire satisfaction. 

Fig. 2 shows the corner 
of a small power-house on a 
private estate. The walls 
were built up between shut- 
tering and every kind of 
CvRios.iiEs NE.« Salisbury. rubbish was used 'in the pro- 

cess, including stone, broken 
brick and tiles, tin and tim- 
ber. Although several re- 
pairs have been effected to 
the building since its erection 
it still seems to perform its 
function adequately. 

Reinforced Concrete Lamp 
Posts. — The advent of town 
planning and the endeavour 
to lay out new estates and 
suburbs on garden city prin- 
ciples suggests very strongly 
that the somewhat pre- 
historic iron street lamp 
standards so dear to gas and 
electrical engineers do not 

276 




m. 










£7G 



Fig. 2. Curiosities near Salisburv. 



r J, CON5rBUCTiaNAl4 
l«EMOrNF-F.PING-«-3 



MEMORANDA, 



DO^oVGU 

cr 




2 'r2cf2 bar5 



— r 



9 3(3uar? . 
topt^riQc; to 
6' square at top 

B 



f 2'3qfuare|fl 



, ^ new door atad \ramz 
jHCTlON AA 




J[:CTIo^^l 5 B 



^Pra 



o 

CM 




jiiii^mig 



Design jor Reinforced Concrete Street Lamp. 

harmonise with the new surroundings. 
This is ver^,- apparent when such a lamp 
standard is trying to look " at home " on 
the village greens of our charming villages. 
To the lovers of rustic art this is impos- 
sible, and although perhaps only a detail, 
a new style of street lamp should never- 
theless be considered, and many will 
agree, with advantage. 

An experiment has been carried out 
with this idea in view on the Woodside 
Housing Estate for the Croydon Corpora- 
tion. The street lamp consists of a tapered 
reinforced concrete post with a link fuse 
chamber at the bottom of standard (this 
work being carried out by the Corporation 
Roads Department). The lantern is of 
Jacobean design, made of cast iron, one 
of the sides being hinged to give access 
to the interior. The illumination has 
given every satisfaction, although there 
was much scepticism when first considered 
as to its efficiency. Where gas is used 
the construction is much more simple, 
as the chamber is not required. 

277 




CONCBEITE^"''''^'''^"'''"^'^^ 



EiNGINBERITSG 



JST 




To Engineers mnd Contractors 



Just now Trade is uncertain and Money is tight, therefore 

you probably hesitate to lay out your money in Plant — yet 

you require additions to carry out your contracts, or to 

secure new ones — 

DO YOU REALISE that 

" UNIVERSAL^ JOIST " and " SIMPLEX " Steel Sheet 
Piling and all the Plant required to drive and to extract 
it, including McKIERNAN^ TERRY AUTOMATIC 
DOUBLE-ACTING and B.S.P. SEMI-AUTOMATIC 
SINGLE-ACTING PILE HAMMERS, PILE DRIVING 
FRAMES, BOILERS, and the "ZENITH " FRICTION 
WINCH, with all necessary tackle 

MAY BE OBTAINED ON HIRE 

with the option to purchase later on if desired. 



THIS MEANS 



a Great Saving in original outlay 
to you, and should you decide 
ultimately to purchase outright, Hiring Fees are taken into account. 



IT WILL PAY YOU TO 
WRITE FOR OUR TERMS, 



Address :—' ' HIRE DEPARTMENT, ' 



BRITISH STEEL PILING CO., 



This applies to the 
United Kingdom only. 



DOCK HOUSE, 



BILLITES STREET, LONDON, E.C.3. 



278 



Please mention this Journal when writing. 



I&^.^S1]^^ MEMORANDA 

CONCRETE AND HOUSING SCHEMES. 

Chester. — The Chester Town Council has instructed the Borough Surveyor to 
obtain information regarding systems of concrete construction in connection with 
the erection of 140 houses on the Heath Lane side. 

Chirbury. — The Chirbury Rural District Council is considering the erection of 
concrete houses in connection with its housing scheme. 

Edinburgh. — The Edinburgh Dean of Guild Court has granted an application 
of the Edinburgh Corporation for the erection of 306 concrete houses under the Wardle 
housing scheme. 

Grays. — The Housing Commissioner for the area has approved the erection by 
the Grays Urban District Council of a further 100 concrete houses on the " Duo Slab " 
system. 

Ipswich. — The Ipswich Corporation has decided to erect twenty-two five-room 
bungalows with concrete walls, at a cost of ;^78o each, and also to build 364 other 
houses. 

Stow-on-the-Wold. — The Ministry of Health has urged the Stow-on-the-Wold 
Urban District Council to carry out its housing schemes in concrete, on the grounds 
of economy. 

Swansea. — The Housing Committee of the Swansea Corporation has recommended 
that a contract be entered into with Messrs. W. Nicholls, Ltd., for the erection of sixty 
steel-frame concrete houses on the Llanerch site. 

Thorne. — -The Thorne Rural District Council has decided to proceed as soon as 
possible with the erection of 166 " Dorlonco " steel and concrete houses and 133 brick 
houses at Stainland, the whole to be completed by July i, 1922. The Public Works 
Loan Board has sanctioned a loan of ;^i 56,000 for the purpose. 

Tilbury. — The Tilbury Urban District Council has decided to invite applications 
for the erection of 250 houses, on the " Winget " concrete block system. 

NEW METHODS AND MATERIALS. 

The following are some further materials and new methods of construction 
approved by the Standardisation and Construction Committee : — 

/. Weston, 203, Hamlet Gardens, Ravenscoiirt Park, London, W.6.—" Westlin " System. — This 
system produces a block built cavity wall, the external blocks being of ballast concrete and the inner 
of clinker. Each block is made with lugs of such a form that the outside and inside blocks lock 
together. 

Messrs. Youns & Co., 6, Queen Anne's Gate, Westminster, S.W.i. — The " Fewac " System of Con- 
struction. — This system consists of a steel frame structure, the uprights in the wall being cased with 
ballast concrete, and the panels between being filled in with zh in. clinker slabs finished mternaUy 
with plaster. Vertical battens are fixed on the outsides of the slabs and the exterior face is finished 
with weather boarding. The system is eUgible for a loan period of 40 years and for two-thirds of the 
amount of the Grant to private builders. 

PROSPECTIVE NEW CONCRETE WORK. 

Amwell. — Bridge.- The Herts County Council proposes to erect a heavy weight-carrying bridge 
at Lowbridge, Amwell. 

Atherstone. — Water Supplv.—The Atherstone Rural District Council has decided to apply for 
the sanction of the Ministry of Health for a loan of £64,000 for a water-supply scheme. 

Bristol. — Waterworks.— The Bristol Water Company has submitted to Parliament a Bill for 
power to construct a new waterworks. 

Brixham. — Reservoir. — The Ministry of Health has held an inquiry into the application of the 
Brixhain Urban District Council for sanction to borroW||£3,ooo for the construction of a reservoir. 

Chichester. — Waterworks. — The Chichester Town Council is considering an apphcation to the 
Ministry of Health for sanction to a loan of £13,000 for extensions at the waterworks. 

Damflask. — Floor. — The Sheffield Corporation proposes to erect a timber house on a concrete 
floor, at the cost of £5,250, at the Damflask Reservoir. 

Denbigh. — Bridge. — The Denbigh County Council has received sanction to the borrowing of 
/4,500 for the reconstruction of Alyn Bridge. 

Dennistoun.— /?oarf. — The Lanark Lower Ward District Committee is considering the construc- 
tion of a new road between Bargeddie and Dennistoun, at an approximate cost of £120,000. 

DvMBARTOy:. — Waterworks. — The Dumbarton Town Council has decided to apply for sanction 
to a loan of £50,000 for waterworks extensions. 

Durham.— J^oai.— The Durham County Council has decided to construct a new road connecting 
Hartlepool, Blackball, Horden, and Easington, at an estimated cost of £270,000. 

279 




/^/^•^/^Tyi7*T»p ^CONSTRUCnONA.!^ 



El^GINI^ERrNG 





\ 



^ 



No other British manufacturer of Concrete Mixing 
Machinery has the experience of which you get the 
benefit when you deal with Stothert & Pitt, Ltd. No 
other British manufacturer possesses the greater con- 
fidence of a greater number of customers. The Victoria 
Mixer is recommended for either large or small require- 
ments. There are models, identical in principle but 
giving a widely varying range of outputs, to meet every' 
demand. Please ask for Catalogue M.D. 103. If you 
are specially Interested in the small hand or power 
driven model, ask for Catalogue M.D. 105. 

(MIXER DEPARTMENT) 

ll.VICTORIA ST.. LONDON S.Wl 



280 



Please mention this Journal when writing. 



k^I^^i^^ MEMORANDA. 



Holyhead. — Harbour Works. — The London & North-Westem Railway Co. is negotiating with the 
Government for a new lease of Holyhead Harbour, and proposes to carry out extensive developments. 
Hornsea. — Sea Wall. — ^The Hornsea Urban District Council is considering the construction of 
sea-defence works, at an estimated cost of £10,000. 

Keighley. — Waterworks. — The Keighley Corporation has received sanction to a loan of /200 000 
for the extension of the waterworks at Sladen Valley. ' 

Llanelly. — Wharf. — The Reliance Fuel Co. ofLlaneUy has decided to construct a new wharf 
at Llanelly, at a cost of about £400,000. 

Portland. — Sea Wall. — The Portland Urban District Council Engineer is preparing plans for the 
Construction of a sea wall, estimated to cost £4,000. 

Wenlock. — Wateru^orks.- — The Wenlock Waterworks has approved of a scheme for the extension of 
the waterworks at Harrington, at a cost of £10,000. 

Weymouth. — Embankment. — The Dorset County Council has decided to construct an embank- 
ment and a dam over the Backwater, at a total cost of £26,305, and has received a grant from the 
Ministry of Transport towards the cost. 

Yarmouth. — Sea Wall. — The Yarmouth Town Council has agreed to construct a sea waU from 
the Revolving Tower to Sandown road, at a cost of £6,000. 

Yeovil. — Reservoir. — The Yeovil Town Council has decided to proceed as soon as possible with 
the construction of a reservoir of 750,000 gallons capacity at Hendford Hill. 

TENDERS ACCEPTED. 

Brentford. — ^The Brentford Urban District CouncU has recommended to the Housing Board 
for acceptance the tender of the Improved Concrete Construction Co. of London, for the erection of 
20 concrete houses, at a total cost of £16,413. 

Bromborough. — -The Bromborough Urban District Council has accepted the tender of Messrs 
Oliver & Co. for the erection of 16 Type " B " houses on the " Cyclops" system of concrete block 
construction, at £965 per house. 

Croydon. — ^The Croydon Town CouncU has accepted the tender of the Hydrauhc Mining Cart- 
ridge Co., for the removal of a concrete foundation bed at the electricitv works, at 40s. per cubic yard. 

Kirkcaldy. — The Kirkcaldy Town Coimcil has accepted the tender of Messrs. Casey & Darragli 
of Stirling, for the construction of a concrete tank at Navitie, and other work, at £23,788 17s. yd. 

Lancashire. — The Lancashire County Council has accepted the tender of Messrs'. Parkinson' & 
Son for the erection of ten pairs of concrete cottages on the Howick, Hutton and Longton Estates 
at £318 per pair. ' 

Macduff.— The Macduff Town Council has accepted the tender of Messrs. G. Duncan & Sons 
of Inverurie, for the supply and fixing of the cast concrete work in connection with its housing scheme' 
at £10,494 105. 4rf. ' 

Middletox.— The Middleton Town Council has submitted to the Housing Commissioner the 
following tenders for the erection of 64 houses on the Boarshaw (North) site : — In concrete : Messrs 
J. H. Bardsley, Manchester : £3,552 per block of four ; in brick :— Messrs. J. Metcalf Manchester • 
£4,180 per block of four. ' 

Northampton.— The Northampton Corporation has accepted the tender of Mr. W. Higgins of 
Northampton, for the erection of 118 concrete houses, at £1,670 per pair. 

Plymouth. — The Housing Commissioner for the area has approved of the acceptance by the 
Plymouth Town Council of the tender of Messrs. E. E. Endicott for the erection of 26 Type " A " houses 
at £885 per house and 26 Type " B " houses at £974 per house, on the " Dorlonco "' svstem of steel 
and concrete construction. 

South Shields. — The South Shields Town Council has accepted the following tender for the 
construction of 72 in., 60 in. and 48 in. diameter brick and concrete culverts at the Brinkburn and 
West Horton Outfall Sewers :— Brinkburn : G. Bailey & Co., Ltd., Newcastle-on-Tyne, £21 446 85 6d ■ 
West Horton: G. Bailey & Co., Ltd., Newcastle-on-Tyne, £6,692 12s. 2d. ^ 'tt 

TENDERS INVITED. 

Durham. — April 13. For construction of two tunnels under Stanhope and Muggleswick Com- 
mons, of a total length of about three miles, together with shaft boring and other work, for the Durham 
County Water Board. • Specifications, etc., from Messrs. T. and C. Ha wksley. Engineers, 62, Broadway 
Westminster, S.W. I. Deposit, £3 3s. <= . . j, 

Manchester.— April 28. The Manchester Ship Canal Co. invite tenders for the construction of 
a reinforced concrete quay, and the foundations for transit sheds, at Trafford Wharf, Manchester 
Docks. Specifications, etc., from Mr. H. A. Reed, Chief Engineer, 41, Spring Gardens, Manchester 
Deposit, £2 25. r ^ , . 

Monte Video.— April 18. Construction of bridge over the Santa Lucie River, for the Ministry 
ot Public Works. Purthcr particulars from Inquiry Office, Dept. of Overseas Trade, 35, Old Queen 
street, S.W. ' 

BUILDING TRADES EXHIBITION. 

Among the firms represented at the Building Trades Exhibition is the Concrete Utilities Bureau, of 
35,GreatSt.Hek'ns, London, E.C.3, at whoseStaiid, No. 108, KmvF, freehteraturcon the manifold uses 
of concrete may be obtained, and the following volumes will be on S3.\e:— Concrete CotlaKes Small 
GaraKcs, and l-arm Biiildim^s, by Albert Lakeman, M.S. A., and Concrete Roads, a recently pubUshed 
work coiitaimng valuable data on concrete roads in the United Kingdom and other countries, coUected 
by the Editor of Concrete and Constructional Engineering. 

A New Block Machine.— A cheap and handy machine for making blocks, slabs and bricks is 
.;!'".?xx^r^ -^^^ ^^ Messrs. Winget, Ltd., at their Stand, No. 123, Row G. This machine, known as 
•?u -n '"^'"^'"^^^'''' '^ particularly suited to the small builder and estate owner. More particulars 
with Illustration will appear in our next issue. 

G 281 



MEMORANDA. 



ICaSCRETFJ 



CHANGE OF ADDRESS. 

The Indented Bar and Concrete Engineering Co., Ltd., have securefl a more 
commodious suite of ofiiccs on tlic first floor of tlie same building in which their offices 
at present are, namely, Queen Anne's Chambers, Westminster, S.W.i. 

Christiani & Nielsen. — We are asked to state that Messrs. Christiani & Nielsen 
have removed from their present offices at 25 and 124, Victoria Street, to more com- 
modious offices at 72-74, Victoria Street, S.W.i. 

NEW COMPANIES REGISTERED. 

Manelite Patent Concrete Machinery Co., Ltd. (173,235)- Registered February 18. To 
acquire Letters Patent No. 119,206 of 1918 for an invention of " Improvements in Macliinery employed 
in the manufacture of Concrete and the like wall blocks." Nominal capital, £10,000, in 10,000 £1 
shares. Directors: F. T. Cutley, 61, Lowther Road, Bournemouth ; H. E. Hawker, St. Peter's Cham- 
bers, Bournemouth; J. H. Jones, 22, Poole Road, Dorset; (1. T. McWilliam, Canford Cliff Road, 
Canford Cliffs, Dorset ; C. I). Newton, 135, Lowther Road, Bournemouth ; and P. H. Parsons, 8, 
Durrant Road, Bournemouth. Qualification of Directors, 100 shares ; remuneration to be voted 
by Company. 

Metallic Plasterinc. and Renovations, Ltd. (173,236)- 43, London Wall, E.C. Registered 
February 18. Workers in metal, cement ^nd other plasters. Nominal capital, £1,000, in 1,000 £1 
shares. Directors : H. C. Gardner, 29, Grosvenor Road, Richmond ; A. E. Saw, " Ravells," Oak- 
leigh Park Drive, Leigh-on-Sea ; and E. Mulroy. Qualification of Directors, one share ; remuneration 
to be voted by Company. 

Ferrate Manufacturing Co., Ltd. (i73,435)- Registered March i. Builders, contractors, and 
manufacturers of concrete. Green Street Green, Farnborough, Kent. -N'ominal capital, £10,000, in 
10,000 £1 shares. l3irectors : S. E. Thomas, Temple Farm, Brinkley ; E. (i. Ilivermore, Bank 
House, Orpington, Kent; J. E. Bennett, Cotfield, Kemsing, Kent ; W. G. Paine, 381, Croydon Road, 
Caterham, Surrey; H. E. Routledge, 13, Tregothenan Road, Stockwell, London, S.W. ; H. B. Byles, 
Hardwick, Long Stretton, Norfolk; G. F. Spreckley, 513, Barking Road, E.13. Qualification of 
Directors, £5 ; remuneration to be voted. 

Excelsior Patent Stone Co., Ltd. (173,476). Registered March 3. F'inedon Buildings, Fine- 
don, Wellingborough. Artificial stone manufacturers and dealers. Nominal capital, £10,000, in 
5,000 £1 preference shares and 5,000 £1 ordinary shares. Directors: D. K. Kingston, Finedon. Quali- 
fication of Directors, £100 ; remuneration to be voted. 



" CONCRETE ROADS," 

a Technical Handbook, carefully Edited and Profusely Illustrated, Intended 
primarily for Borough Surveyors, Municipal Officials, Engineers, Road 
Contractors, and all others interested in Modern Road Construction. 

Now Ready, 8s. By Post, 8s. 6d. 

From CONCRETE PUBLICATIONS, LTD. (Publishing Dept.). 

4, Catherine Street, ALDWYCH, W.C.2. 

PRESS APPROVAL. 

The Builder. — "This book is published at an opportune time. ... It is a handy and well- 
arranged volume, which may be recommended to all interested in the subject dealt mth." 

Municipal Journal. — " This admirable book can be safely recommended to municipal engin- 
eers and their assistants." 

Surveyor. — " Road engineers will warmly welcome the book on Concrete Roads. It is very 
well illustrated with photographs of the roads. The book mil be found extremely useful by all 
road engineers, and make a valuable addition to their libraries." 

Financial News. — "This question is 'discussed fairly and without prejudice in Concrete 
Roads. . . . The book forms^a valuable addition to literature on the subject." 

Motor Transport. — "A well-illustrated book . . . which deals with this important subject m 
a very lucid and interesting manner." 



2S3 



CONCRETE 

AND 

CON&TEUCTIONAL ENGINEERING 



Volume XVI. No. 5. London, May, 1921. 

EDITORIAL NOTES. 



BUILDING TRADES EXHIBITION. 

It is certainly unfortunate that the Building Trades Exhibition should have 
coincided with the gravest industrial crisis that the country has witnessed since 
the war. The trade depression of the previous months had unavoidably made 
itself felt in the building industr}-, and a period of hesitancy had set in. It was 
hoped, however, that the Exhibition would act in some degree as a stimulus 
both to the layman and to the builder. The former w^ould see that the prices 
of certain materials and commodities were undoubtedly lower than those quoted 
at the last exhibition, and he might thus be inclined at last to put in hand work 
which had hitherto suffered continual postponement owing to high cost. And 
the latter might feel disposed to purchase certain items of new equipment and 
plant, the acquisition of which had been delayed until a comprehensive comparison, 
such as is only possible at these gatherings, could be made. Although the attend- 
ance at the exhibition was good the enthusiasm of last year was lacking, for 
the minds of many visitors were occupied with other things. Even municipal 
housing undertakings have become infected with this spirit of irresolution, and 
in many instances large schemes are held in abeyance. 

CONCRETE CONSTRUCTION. 

During the year many of the patent systems of construction have under- 
gone practical tests ; some have failed and dropped into oblivion, others have 
survived, and certain new ones make an appearance this year for the first time. 
As heretofore concrete appeared in a multitude of guises showing its versatility 
and its suitability for numerous purposes. Although it was the exhibition of 
1920 — the first post-war gathering— that showed the most marked increase in 
concrete development, nevertheless this year's exhibits testified to the increasing 
use of this material, and it must have been apparent to the most casual observer 
that the new uses to which concrete was put during the war were no mere emer- 
gency measures, but were legitimate uses of one of the finest, and, let it be remem- 
bered, one of the oldest of building materials. Last year, to manv. the sight 
of so large a number of block-making machines at work constituted a diversion ; 
this- year, however, their interest was of a more practical nature, comprising 
enquiries as to comparative costs, daily output, shape of the block produced, 
method of tamping, and the like. 

283 



BUILDING TRADES EXHIBITION. iCQMZBETE] 



THE SURFACE TREATMENT OF CONCRETE. 

Nevertheless in one direction, at least, we would have wished to see 
concrete far more prominent. A casual visitor to the exhibition would have 
left convinced that, whatever can be done with concrete, there is one purpose 
for which it is no use, and that is to produce a fine richly textured surface ; it 
cannot, in fact, compete with the best quality brickwork or masonry. It 
may be suitable, the casual visitor would argue, for structural work of all 
kinds, and for smaller domestic work, but in monumental architecture, where 
beauty and colour of texture are important considerations, if it be used its 
face must be hidden. This is fortunately an utter fallacy, but evidence to 
prove it is sadly lacking in this country. We have drawn attention to this matter 
on previous occasions and we shall continue to do so in the future. Just as 
the manufacturers of bricks display their choicest effects of walling, so too concrete 
machine manufacturers should have displayed portions of walling built with 
various rich aggregates and treated in various ways. Here is a vast area for 
conquest. 

MUNICIPAL AND OTHER EXHIBITS. 

The growing importance of the municipality as a constructive agent, both 
in matters of engineering and of building, was also manifest, and the segregating 
of exhibits of particular interest to such bodies to the gallery was an excellent 
innovation. The exhibition, indeed, was primarily one of practical things, the 
aspects of building as a fine art were not prominent. There were, of course, 
exhibits of rare and beautiful timbers, of exquisitely marked marble, and of 
fine paintwork, but the sense of these things was overborne by a more profuse 
abundance of hot water apparatus, kitchen equipment, concrete mixing machinery 
and chestnut paling. Another comparison between the recent exhibition and 
that of 1920 might be made by stating that the tone of the former was saner 
than that of its predecessor. The period succeeding the war and preceding the 
1920 exhibition witnessed a veritable outbreak of inventive ingenuity. Much of 
it, however, defeated the very object for which it should have been devised 
by substituting one kind of complication for another ; it was a period of " gadgets," 
each inventor seeking to outdo his neighbour, forgetting that each addition added 
to the cost and likewise to the number of moving parts, so increasing the risk 
of a breakdown. Thus the visitor, fascinated as he was by a demonstration 
of an automatic " washer up," or by a vision of a super-dresser with a place 
for everything, was deterred from buying them, partly on account of their cost 
and partly on account of conservatism ; that deplorable, but nevertheless almost 
universal, human characteristic. Only the soundest of this class of commodity 
has survived the year's test, and emerged solvent. 

It is in observing, or perhaps in merely feeling, such differences as those 
indicated that the pulse of the age — the pulse of the fleeting moment — can be 
apprised, and the almost insensible change, that seems ever without intermission 
to sway the course of our progress from following a direct line, be noted. 

GENERAL ARRANGEMENT. 

We notice that a contemporary draws attention to the lack of cohesion in 
the arrangement of the exhibits and in the design of the stalls. It is an opportu- 

284 



1 



[&^^Em?^^ THE CONCRETE INSTITUTE. 

nity for a comprehensive layout scheme, which requires architectural knowledge, 
and it is suggested that a committee of three be formed composed of an architect, 
a trader, and a member of the officiating committee whose function it would be 
to " approve or disapprove and advise upon the design of the stalls," and whose 
decision would be final. Much invective will doubtless be hurled at the head 
of the originator (in this instance Professor A. E. Richardson, F.R.I.B.A.) of 
this suggestion, for it will be felt that it savours of interference with the liberty 
of the subject ; of autocracy. For our own part we heartily concur with the 
suggestion, and agree, furthermore, with the writer of the article when he points 
out how superior is the arrangement of such a gathering when it is organised 
on the Continent or in America. A demand for beauty in mundane things is 
incipiently asserting itself, for in another contemporary we have been delighted 
to see a plea for better design and colouring in such objects of use as street lamps, 
pillar boxes (though the design and colour of the latter is at present excellent) 
and sand bins. Surely the Building Exhibition might be expected to give its 
support to such a laudable endeavour. 

Thus in next year's exhibition we shall eagerly look for two improvements, 
one affecting the general arrangement of the hall, and the other affecting that 
particular class of exhibit in which we are naturally most interested. 

A STEP FORWARD ON THE PART OF THE CONCRETE INSTITUTE. 

A short time ago we recorded the fact that the Council of the Concrete Insti- 
tute were considering the formation of a new class of membership. The fons 
et origo of this was that the Institute had, from time to time, received applications 
from foremen or from clerks of works and others who, while they could not be 
included in the category of professional men, nor of those who had had University 
training, yet had a thorough practical knowledge of concrete work. It was felt 
by the Council that the time had arrived when such persons should be admitted 
to the advantages of membership of the Institute, and it has been decided that 
a new class should be created and that its members should be known as Licentiates, 
the licence to be held under conditions laid down by the Council. 

This we consider a very wise and commendable step on the part of the 
Council and one that should be of mutual advantage to both the Institute and 
the Licentiates themselves. On the one hand the scope of the Institute's activities 
and influence is widened and the organisation will always be able to obtain, at 
first hand, the opinion of the practical expert. On the other hand, the licentiate- 
ship of such a body as the Concrete Institute will give a certain status to the 
holder which will be a guarantee of his efficiency, and membership of this class 
will include many advantages and privileges which the Institute can confer. 

We welcome this move, too, because it is in conformity with the spirit of 
the age, a spirit which is leading more and more towards a closer co-operation 
and a better understanding between the professional and the practical worker. 

GENERAL NOTES. 

DESIGNS FOR PROPOSED CONCRETE WORK. 

It has been our practice hitherto, in these pages, to describe and illustrate 
work actually carried out, but we feel that it might be helpful and suggestive, 
as well as of general interest, to publish designs of proposed buildings, together 

285 



GENERAL NOTES. [CDNCRETEl 



with a brief description of same, where it is suggested that concrete or reinfcjrced 
concrete should be the principal material used in the construction of such work. 
We, therefore, invite architects, engineers and others to send in such proposed 
designs, accompanied by brief descriptive notes. 

A contractor's page. 

There are often points of difficulty that arise in the course of executing 
large building and engineering works ; these have to be solved on the job by 
the superintending engineer or clerk of works. We believe it would be of general 
interest if such problems and their solution were briefly described from time 
to time, and we therefore invite engineers, contractors and others concerned 
to send us information of this kind for publication, together with diagrams or 
photographs, where such are needed for explanation. 

At the present time when greater attention is being given to the general 
layout of the plant, notes on this question would also be useful. 



THE USE OF CLINKER FOR BLOCKS AND SLABS. 

In a recent issue of " Housing " the Ministry of Health emphasise the need of 
adhering to their specification when manufacturing blocks and slabs of clinker, 
for they state that unburnt coal is frequently found in their composition. The 
article goes on to say that : — 

" It is necessary to direct attention to this matter, as serious results may ensue 
when such blocks and slabs are used. In a recent case certain slabs were tested 
and it was found that after immersion in water for one night, they had burst. 
In another, the blocks were finished fair face in fine ballast concrete, and after 
being built into the wall the face cracked and broke away while the slab itself 
was fractured. In each case coal was exposed on the line of fracture. 

"It is desirable for all users of blocks or slabs, which are not under proper 
technical supervision in accordance with the specification but are bought from 
manufacturers, to insist on a guarantee from the manufacturers that they have 
been made in accordance with the Ministry's Specification for Cement Concrete 
Building. In some cases, the sand specified for the clinker aggregate is not 
required, and it is found that a stronger block or slab can be made when the 
sand is omitted than when it is added, but this depends entirely on the nature 
of the aggregate and can only be determined by experiment. 

" Where the blocks or slabs are to be finished with plaster or rough cast it 
is necessary to see that they are cast with a face sufficiently rough for the purpose, 
to avoid unnecessary labour in scoring after they are built to provide a key." 



286 



-% 



^ 









Stones Nos. 6 and 7 at Stonehenge after Adjustment. 
[See article, p. 287.) 



E 



CONSTCUCTlOT>(AL 
ENGIMEERING — ; 



STONEHENGE. 





iii 


h 


f ]• 




11 




STONEHENGE. 


^wm 


Ite 


AN ACCOUNT OF THE WORK CARRIED OUT 
BY H.M. OFFICE OF WORKS. 


. /S^^Wijt^'^'^i'^JwI /■ 


^w 


J 



An interesting instance of the use of reinforced concrete in iireserving our 
ancient monuments has recently occurred at Stonehenge, and by the courtesy of H.M. 
Office of Works, we are able to give the following particulars and accompanying 
illustrations of this work. — Ed. 

It will be remembered that Stonehenge was presented to the nation by Sir 
Cecil Chubb in 1918. At that time it was realised that the stability of many of 
the stones, still maintaining an upright position, was very uncertain, and His 
Majesty's Office of Works, in the spring of 1919, undertook a most thorough 
survey of the stones under the direction of Sir Frank Baines, C.B.E., M.V.O.,in 
order to ascertain the conditions of stability and other details concerning each 
individual stone. Before embarking upon a detailed account of this work, a short 
description of the whole erection may be of interest. 

Stonehenge is the name given to a number of large stones standing on Salisbury 
Plain, near Amesbury. Its exact date is unknown, but it has been computed by 
Sir Norman Lockyer to be as early as 1780 B.C. The stones are arranged in 
circular formations ; the outer circle of Sarsen stones, which average 14 ft. high 
above the ground, has a diameter of 97 ft. 4 in. to the inner face. Of the thirty 
uprights and thirty lintels which originally comprised this outer circle, only 
sixteen uprights are now standing, and only five lintels are still in position. 
Within this outer circle is a ring of blue stones whose geological formation is 
not of local origin. These stones are smaller and without lintels ; only nine of 
them are standing to-day. Within the circle of blue stones are five Trilithons, 
arranged in the form of a horse-shoe. Each is composed of two imposts and a 
lintel across the top. The largest of the imposts is the famous " leaning stone," 
which is said to be the largest native stone in England, being 22 ft. high above 
ground with 8 ft. below. In the seventeenth century some excavations were 
made to this stone which caused it to assume an even more dangerous position, until 
in 1901, when it was moved upright, it inclined at an angle of 25°. To-day six 
of the imposts are standing and two lintels are in place. Within the TrHithon 
horse-shoe there is yet another circle composed of about twelve small blue stones. 
Close to the centres of these circles lies the so-called " Altar Stone." Outside the 
circles lie the Hele Stone, the Slaughter Stone, the S.E. and the N.W. stones. 
It is calculated that originally there must have been a weight of about 1,500 tons 
of stone used in the construction of the circle. To-day only about half the stones 
are standing, but none has fallen for about twenty years. 

The first operation in connection with the survey was to drive in six pegs 
round each upright stone ; these were then connected to the main theodolite 



287 



STONEHENGE. 



[CQNCBEIEJ 



survey lines. By means of plumb lines offsets were taken at 12 in. vertical 
intervals, or at points where the contour of the stone changed. These surveys 
were then plotted out and four elevations and a plan at ground level were made of 
each stone. In the case of those stones which appeared to be dangerously out of 
the vertical, horizontal cross-sections were drawn at every foot in height. The 
centres of gravity of the stones were plotted on the elevations, from which a line 
of thrust was drawn. In the case of stones carrying lintels, the weight of these 
was combined with the line of thrust (tests with fragments of Sarsen stones 
showed a specific gravity of 2*4, which equals 150 lb. per cubic foot) and a 
wind pressure of 40 lb. per square foot was assumed. The modulus of the 
horizontal section at ground level was found graphically, and thus the stress on 
the stone due to bending and due to the direct load was obtained. The maximum 
stresses in the case of No. 7 stone were, for compression, 78 lb. per square inch, 
and for tension 37 lb. per square inch. 




Fig. I. Survey made in May, 1919. 

Part of the survey consisted in a detailed examination of each stone. Every 
crack, hole and fissure was carefully noted and recorded by means of sketches and 
photographs. As a result of this survey a report was prepared and recommenda- 
tions were made to deal with stones Nos. i, 2, 6, 7, 29 and 30, all of which were 
found to be in theoretically unstable condition. A copy of this report was presented 
to the Ancient Monuments Board for England and Wales, and after discussions 
it was decided to adopt the recommendations. It was also arranged that the 
Society of Antiquaries should nominate a representative to supervise the work of 
excavation which would necessarily be entailed. The Society undertook to bear 
the cost of any extra work involved in sifting and examining excavated material. 

The first stones to be dealt with were Nos. 6 and 7, which were upright 
stones dependent for the maintenance of their position upon temporary timber 

288 



E 



ClON5TKUt-naM. 
EMG1TVEEJ?1NG 



a 



STONEHENGE. 



struts. These stones are situated on the southern side of the outer Sarsen ring. 
These two stones are connected by a hntel, but the hntels to the adjoining stones, 
5 and 8, have disappeared. These stones inclined in opposite directions, No. 8 
to the east, at an angle of 7°, and No. 7 to the west (inwards), at an angle of 11°. 
No. 6 stone, which weighs about 20 tons, stood 13 ft. above the ground, and over- 
hung its base by some 15 in. at a point 12 ft. above ground level. No. 7 stood 
about the same height and overhung its base by about 19 in. The lintel is approxi- 




mately II ft. by 3 ft. by 2 ft. thick, and weighs about 5 tons. On the underside 
are two dowel holes which fitted over dowels in the uprights. 

The first job was the removal of the lintel, and for this purpose a cradle of 
8 in. by 8 in. pitch pine timber was bolted round, thick felt packing being inserted 
between the timber and the stone to prevent marking. On November 27th the 
stone was raised from its seating, by means of a 7-ton hand derrick crane with a 
40 ft. jib, and safely lowered. The next operation was to fit timber cradles around 
stones 6 and 7. Many methods of moving the stones were considered, but it was 
finally decided to adopt the principle employed in using the ordinary dumpy 

c 289 



STONEHENGE. 



[QONCBETEJ 



level, viz. : to support the stone from the ground by means of travelling screw 
jacks, which would enable the stone to be moved in any direction, and would 
also permit of excavations being carried out under it, and finally would prevent 
the stone from tilting sideways. The method adopted was to fix two 14 in. by 6 in. 
R.S.J., 20 ft. long, under each cradle, just clear of the ground and passing 
either side of the stone. These joists were connected by steel angle cleats to the 
cradle and four raking shores were carried down from the top of the cradle to 




Fig. 3. Method of Moving Stone to their Original Position and Levels. 

the ends of the joists (see Figs. 3, 4 and 5). The four jacks were then placed 
under the ends of the joists. 

As already stated, a representative of the Society of Antiquaries was present 
during the operations, and in order to assist him in recording the exact position 
of each find the excavations around the stones were made with great care. The 
ground was squared into i ft. squares and the excavations were made 6 in. at a 
time from a fixed datum ; in this way, by means of co-ordinates, the exact position 
of any finds could be recorded. These consisted chiefly of stone mauls, fragments of 
stones, and of Roman British pottery, and a few coins. Prior to beginning the 
excavations, however, the stone was stayed in four directions by wire ropes. 

290 



r »■ cossrnvcTKHAil 

L<i^gNOfNEEBlNG — | 



STONEHENGE. 




Fig. 4. Stone No. 7 from S.E. after being moved Upright, showing Timber Cradle on Stone, and Excavation 

ROUND THE BaSE OF StONE. 




Fig. 5. Stone No. 7, after being moved UrKioiix, bUowiNG Ti.mulr Ckapi 1; kounh SmNi. kesiing on Steel Joists 
WITH Screw Jacks underneath used in bringing the Stone Upright. 



C 2 



291 



STONEHENGE. [CDNCRETE: 



The excavation extended some 2 to 3 ft. back from the face of tlie stone, and 
beyond that four | in. steel plates 4 ft. square were laid on the solid chalk as 
bed-plates for the jacks ; in one case concrete had to be used to give a firm and 
level foundation, but, for the most part, a bed of solid chalk was encountered 
18 in. below the ground level. Before the stone was raised by the jacks wire 
rope slings were passed under the stone, through a channel cut in the chalk bed, 
and made fast on either side to the cradle. This, of course, was to prevent any 
possibility of the stone slipping through the cradle when it was raised. 

By means of alternately raising the jacks on the inside and lowering the 
jacks on the outside, i in. at a time, No. 7 stone was brought back to a vertical 
position on January 27th, 1920. The ground was then excavated beneath the 
stone for a depth of 12 in., and a concrete bed 12 in. thick, reinforced with | in. 
rods in both directions, was next inserted with the utmost expedition under the 
toe of the stone. No. 6 stone was then brought into the upright in a similar 
manner and the concrete bed extended under it, the two separate concrete beds 
being connected by projecting steel bars which were left for that purpose in the 
bed of No. 7. Before finally fixing the stones in their new positions it was necessary 
to ascertain that these were absolutely accurate. The evidence at the base was 
insufficient, but it will be remembered that on the top of the stones were dowels 
4 in. high and g in. in diameter. Corresponding mortices, worn larger in course of 
time, were in the lintel ; it was essential firstly that these should coincide ; secondly, 
that the lintel should conform to the general line of the circle. To lift the lintel 
into position for a trial would be difficult, owing to its weight. A template was 
therefore made out of i in. boards with holes cut for the dowels. By this means 
the position of the uprights was exactly adjusted by traversing the jacks, and 
plumbings were taken on the four faces of the stones. Another template, 60 ft. 
long, and cut to the circumference of the outer Sarsen circle, whose diameter was 
97 ft. 4 in., was then laid on the ground so that it just touched the inner faces 
of stones 5 and 10 (these being the adjacent standing stones to 6 and 7). Stones 
6 and 7 were then finally adjusted, so that their inner surfaces just touched the 
template. A lintel is standing on stones Nos. 4 and 5. A dummy was made to 
bridge Nos. 5 and 6. In this way the continuity of the circle by means of lintels 
4 and 5, 5 and 6, 6 and 7 could be observed. 

In order that the dowels and dowel holes might fit, it was decided to make 
lead caps to fit over the dowels and fill the space between the dowels and the 
holes. These were most accurately made by taking casts of each dowel and dowel 
hole, and then making a lead cast of the intervening space (see Fig. 8). The cap 
for No. 7 stone weighed 170 lb., and that for No. 6, 69 lb. On March 17th the 
lintel was lifted back, and final slight adjustments amounting to fractions of an inch 
were made. The final operation of securing the uprights in their new positions 
was then begun. As a preliminary, the bases of the stones below ground were 
thoroughly cleaned down with water and wire brushes ; likewise the concrete 
bed. Concrete, reinforced with f in. rods, was then placed on the beds round the 
stones and brought up to within 12 in. of the ground level at its outer edge, and 
3 in. from the ground level against the stones. The lintel was then slightly raised 
in order that the caps might be fitted. No. 7 cap being inscribed, " May, 1920," 
and having a George V. shilling fitted in the top. The caps required a small 
amount of chipping before the lintel fitted down closely, and any interstice was 

zgz 



E 



CONSTBUCnCNAU 
EMGrNE£KXNG--3 



STONEHENGE. 



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293 



STONEHENGE. 



[jXJNCi^lYl 



caulked with lead. When the concrete had set, the wire rope slings were cut off 
and the ends turned down and cemented into holes left in the concrete for that 
purpose. On May i8th, the ground was returfed and the operation thus completed. 
Stones Nos. 29, 30, i and 2, were treated in exactly the same manner. They 
presented more difficulty, however, as they were heavier and closer together. 




jjOjotUr O^ 




NO 7 LOOKING N E 



VIEW fP^OM I>4!:Dc Of CfXLE 
NOTE yC fWrW i'-^ «ck:o<« frtt*M3 ^4Si^.<r* of jAtnu 



KiO 6LCXXJNC SV 




^■^ (W-.- ttf t^f-m of /*^* j' ' 



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Fig. 7. Final Position's of Stones 6 and 7. 




PLAsitR Casts of Dowels anu I' "sn 



HEM AND DOWIL 11,1.1.5 >-R;..Ni NV}!!' H LlAD CaPS WERE 

i „., Stones 5 and ;. 



294 



r », OOMSTBUCnONALl 



MACHINE SHOP, SMETHWICK. 




i REINFORCED CONCRETE 
MACHINE SHOP AT 
SMETHWICK. 




The building illustrated herewith has been erected over the steel storage yard of 
the Birmingham Railwa}' Carriage Company, at Smethwick, in order to provide 
additional working space. Owing to its position in an already crowded portion 
of the Company's area, it was necessary that the site should still be available 
for storage purposes, and the whole of the building is therefore erected on columns. 
The distance between the columns supporting the building is necessarily large,, 
and allows for railway tracks to be laid on the ground between the columns and 
under the building, where the storage yard is still being continued. 




Reinforced Concrete Maciii; 



SMETHWICK : General View. 



The building is built entirely of reinforced concrete on the " daylight " 
principle, the light being admitted through large window areas, separated only 
by the reinforced concrete columns, on all sides of the building. 

The building contains two storeys, and the two floors and the roof are each 
constructed as reinforced concrete slabs supported on reinforced concrete beams 
and girders, which take the loads to the columns. 

The first floor wfll carry a superimposed load of 2 cwt. per square foot, and 
has been especially reinforced to carry the heavy machinery which will be installed. 
The second floor is designed to take a load of i| cwt. per square foot. 

The reinforced concrete columns which support the building are taken down 
to a depth of 13 ft. below ground level, and from that depth mass concrete piers 

295 



MACHINE SHOP, SMETHWICK. 



[QONc^rm 



are taken further down through the ashes which form the upper part of the subsoil 
to a firm clay bottom, which in some cases was only found at a depth of 30 ft. 

The elevation of the building is relieved by two lines of brick dadoes, which 
run around the structure at the level of each floor. The brick dadoes are finished 
off with concrete copings, and the windows extend from this coping to the bottom 
of the reinforced concrete beam of the next floor 




First and Second Floors. 
Reinforced Concrete Machine Shop at SMETHwncK. 

Access to the building for the employees is by three reinforced concrete 
staircases. Materials are elevated by lifts installed in the corners of the building, 
while heavy machinery is hoisted up through a central hatchway in each of the 
floors, the lifting table being supported by the roof beams. 

The building was designed throughout by Messrs. Peter Lind & Co., of 2, 
Central Buildings, Westminster, S.W.i, who also carried out the constructional 
work with their own staff of expert workmen. 

296 



I a. torJijruucTKMAxi 



THE CONCRETE INSTITUTE. 




THE CONCRETE 
INSTITUTE. 



MONTHLY NOTES, 

By the SECRETARY. 



THE CONCRETE INSTITUTE AT THE BUILDING EXHIBITION. OLYMPIA. 

WEST KENSINGTON. 

The official visit of the Institute on Wednesday, April 13th, was well attended- 
and the members were conducted to various stalls of special mterest. Mr. A. 
Alban H. Scott, F.S.Arc, kindly acted as chief guide. Mr. H. Kempton Dyson, 
M.C.I., gave an address on the same afternoon on the subject of " Building m 
Concrete," and showed on the screen some film pictures cognate to the subject 
of his lecture 

On Tuesday, April 19th. the President (Mr. E. Fiander Etchells) and the 
Council gave a luncheon in the Pillar Hall, at which were present, amongst 
others, as guests of the Institute :— The Most Hon. the Marquis of Salisbury, 
P.O., K.G., etc. ; The Right Hon. the Lord Riddell ; Sir Frank Newnes, Bart ; 
Sir Ambrose Poynter, Bart. ; Sir John Thornycroft ; Mr. S. B. Russell, F.R.I.B.A., 
and Major Wightman Douglas, of the Ministry of Health ; Mr. Illesley (Ministry 
of Health) ; Sir Charles T. Ruthen, O.B.E., F.R.I.B.A., President of the Society 
of Architects ; the Presidents of the Institute of Builders and of the London 
Master Buildei^' Association; Mr. H. Greville Montgomery, etc., etc. There 
was a large attendance of members and their friends. After the loyal toasts 
had been honoured, the Marquis of Salisbury proposed the toast of the Concrete 
Institute, to which the President responded, and the latter then proposed the 
toast of the Press, coupled with the name of Lord RiddeU. After the toast 
had been acknowledged, Mr. A. Alban H. Scott gave an address upon the subject 
of " Science, Efficiency and Progress versus Stereotyped Building Acts. 

On Saturday, April i6th, in the afternoon, a visit was paid to the new build- 
ings being erected in Sumner Street, Southwark, for the Amalgamated Press, 
Limited, from the designs of Messrs. Herbert O. Ellis and Clarke. Mr. E. Lawrence 
Hall, M.C.I. , took charge of the party. Further particulars of this building will 
be given in a subsequent issue. 

RECENT ELECTIONS INTO THE INSTITUTE. 

Honorary Member: — Robertson, Sir Robert, K.B.E., F.R.S. 
Associate Members :— Biddulph, Charles Hubert. 

Burns, Thomas Frederick. 

CoRYN, Allen Herbert. 

Hatton, Albert Edward. 

Pearce, Harold Ellis Dallas (from Student). 
Licentiates : — Mantle, Christopher W. 

MHATREf Succaram Vassadeo. 
Graduate :— Wood, George. 

Student : - Cofsev, Arthur George. 



297 



THE CONCRETE INSTITUTE. [CQNCI^ETE] 



CONCRETE AGGREGATES— cont/nued. 

(36) FUnt (North Wales) :— 

General Description : — Lead mine crushed spar. 
Source, and locality of same : — Various points in the county. 
How obtained : — From large heaps. 
From whom obtained : — Various lead-mining industries. 
Is available quantity limited P — Almost unlimited. 

7s there any provision at or near source for washing or crushing ? — Already crushed 
and washed. 

Price per cubic yard, and where delivered : — About 15. -^d. at the mines. 

Is composition uniform ? — Yes. 

Kind of stone or coarse material : — Hard limestone and spar. 

Shape of particles : — Angular. 

Size of particles :- — \ in. and down. 

Impurities present : — None. 

Source of information : — County Surveyor, Mold, Flint. 

General remarks : — Very useful Concrete material. 

(37) Folkestone (Kent) r^Compton Hill gravel and sand, containing 25 per cent. 

of loam. (R.C.B.).* 

(38) Glossop (Derbyshire) : — Grit-stone inclined to be fiat and dirty ; is not strong. 

(R.C.B.)* 

I am enabled to publish the following reply to Mr. G. B. R. Pimm's letter which 
appeared in the last issue of this paper : — 

" With reference to Mr. Pimm's letter, published in the April issue of Concrete 
AND Constructional Engineering, I have not come across the river-bed deposits 
referred to, but should like to point out that the material in the refuse heaps is dan- 
gerous to the Concretor, not only from its contamination with clay, but on account 
of its mechanical weakness. I have found that after washing the sand to remove 
external clay many of the remaining grains can be broken in the fingers, owing, pre- 
sumably, to partial disintegration, and the washed material thus forms a treacherous 
concrete aggregate. It is to be supposed that this state of partial disintegration 
does not exist in the river-bed material. 

" Yours faithfully, 
"4, Lloyds Avenue, "R. C. Branston. 

"London, E.C.3. 

"April 14, 1921." 



STRESSES IN STEELWORK. 

By S. BYLANDER, M.C.L, P. Chairman J.I.E. 
Abstract from a paper read at the One Hundred and Second Ordinary General 
Meeting of the Concrete Institute on March 31st, 1921. The President, Mr. E. 
Fiander EtcheUs, was in the Chair. 

I PROPOSE, in this paper, to deal with stresses in structural elements and connections 
for steelwork in building construction, and not with principal and secondary stresses 
in the main structural steel members. 

Unit Load. — I am accustomed in my office to use a unit of weight of one kip (K), 
a term abbreviated from " kilo-pound," meaning 1,000 lb., for the reason that it 
will save probably 10 per cent, in the cost of the calculations. Also, it is simple, and 
reduces the work of checking, as only one unit is used instead of three, viz., tons, cwts. 
and lb. For small loads pounds are used, but only a decimal part of a kip, and 
therefore this need not be considered as a separate unit. One kip is used in calcula- 
tions instead of one English long ton of 2,240 lb. 

Basis Stress. — It will be found that in the majority of cases 10 kips per square 

inch is a safe unit stress for steelwork. It has therefore occurred to me that this unit 

of 10 kips could be adopted as a basis stress for structural steelwork, and that for 

varying conditions this basis stress could be multiplied by tabulated stress factors 

* See previous issues for Index letters. 

298 



I^gSS^^SPr^g STRESSES IN STEELWORK. 

varying for pillars, beams, girders and elements of structural details. The advantage 
of adopting the idea of a standard basis stress for a particular material would tend 
towards simplicity, as the basis stress could be varied at will, while the stress factors 
would remain unchanged, and by this means, the engineer's requirements for the 
structure could be modified to suit the quality and cost of work desired and the safety 
factor permissible. Such variation in the basis stress would affect all the various 
calculations, without the necessity of specifying in detail for every one — simply by 
changing one figure only. 

The stress factor will represent the increase or decrease of the basis stress due to — 

1. Method of loading. 

2. Shape and building up of the cross section and parts of structural member. 

3. The mode of riveting bearings and abutting surfaces and connections. 

4. Slenderness, flexure and stresses from other causes than intentional loading. 

5. Grade of workmanship, etc., and others. 

The stress factor is chiefly defined by theory, and can be computed theoretically 
under assumptions generally accepted in engineering practice. Some must of course 
be determined rationally from engineering and mathematical reasoning. 

The stress factor for a definitely stated condition, therefore, is not variable, but 
represents a mathematical function, while the basis stress may be varied by reason of 
judgment in each case. Ten kips stress is safe for ordinary pillars in buildings, and 
might be constant and permissible from one up to sixty radii for the sake of simpUcity. 
Above that limit, the stress must be reduced as determined by a slenderness stress 
factor. The shear stress on gross sectional area of webs for girders, and on rivets, 
could safely be set at ten kips, as a standard working stress for rough calculations.- 
A narrow riveted compression flange under ordinary conditions, riveting and slender- 
ness, could also safely be stressed to 10 kips per square inch of the gross area. Let 
us now take the tensile stresses, which, when only the gross sectional area is known for 
built up sections, and 20 per cent, reduction is made for rivet holes, the safe stress 
might be set at 14 kips or i"4 of 10 K per square inch on the gross area, while the stress 
on the net area might be set at 17 kips (about 7 J tons). In exceptional cases, where 
no secondary stresses have to be allowed for, I would even go as high as 20 kips per 
square inch on the net area. This might be considered the maximum allowable actual 
stress from all causes. You have therefore the simple and often admitted comparison 
that working compression stresses on the gross area should be calculated as only half 
of the working tensile stresses on the net area. 

For tension only, the maximum stress would be twice the standard basis stress 
or the tensile stress factor would be two. 

The basis stress of ten would be applicable to struts of moderate slenderness, 
even up to 90 radii, in favourable circumstances, when elements in compression such 
as stiffeners, plates and angles, shear on-bolts and rivets and less important members 
or details are only roughly calculated. 

For more accurate calculations, the proper stress would be ascertained through 
multiplying by the appropriate factor. 

Limits o£ Stress. — When flexure and other secondary stresses occur, there should 
be two limiting stresses specified, the lower maximum for the principal stress 
only, and the higher maximum total stress being for primary and secondary 
stresses added together. The requirements being made in such a way as to 
permit an actual increase stress, if all the stresses have been fully ascertained and 
added. 

Instead of putting a penalty on the designer who takes into account all conditions, 
a premium should be offered for thorough analysis of stresses. In other words, for 
rough calculations use a lower stress than for accurate calculations. For instance, a 
pillar with a slenderness of 30 should not be calculated for a stress of 13 K, unless it 
is ascertained that the application of the load on the elements of the sections is such 
that- the actual total stress is not excessive owing to a flimsy section with unstiffened 
flange or locally increased stress due to application of the load. There is another 
principle on the problem of stresses in pillars, that the bending stress should not be 
added to the stress due to flexure for a very slender pillar in order to ascertain the 
total stress, as the maximum bending stress and the maximum flexural stress usually 
do not occur at the same level or point. 

299 



_S\ BYLANDER. ICDNCBETE] 

Beams. — It is indeed difficult to believe that the same kind and amount of stress 
will occur in all beams which are calculated for the same bending stress. 

By the tabulation of suitable stress factors, working stresses could more easily 
be ascertained to suit more closely the actual conditions. Stress factors would be 
provided both for body and details, and elements of a structural member and a principal 
stress factor may be obtained by multiplying several subsidiary factors. 

The stresses must be dependent on the quality and uniformity of the material, 
the (luality of workmanship in the manufacture, and accuracy in fixing together the 
final structure. 

Compression Generally. — Pillars, struts and girder flanges in compression are 
similarly treated, except that the reduction in stress for a girder flange is less than for 
a pillar having the same slenderness ratio. This is so because the flange stress in 
a girder varies from zero at ends, where freely supported, to a maximum at or near 
the centre of span, and therefore the flexure should be less. 

Beam Connections. — I have analysed the stresses which may be expected to occur 
in the rivets for the connection angles or the cleats at the end of a beam, or what may 
be termed the " beam-end connections." The usual rough method of ascertaining 
the strength of a connection would be to take the strength of one rivet and multiply 
by the number of rivets, and the product would be assumed to represent the total load 
the connection could carry ; but this is obviously not safe for all connections, as the 
actual strength of a standard beam connection may be as low as one-quarter of the 
above. 

The assumptions made for calculating the strength of the connections are, like 
other assumptions for riveted work in the theory of structures, only approximately 
■correct. It should never be forgotten that assumptions are usually based on perfec- 
tions which do not exist ; however, they are the best assumptions which we have 
so far succeeded in finding. It would be interesting to have tests made to compare the 
actual strength of connections with those calculated. I think, however, that the 
calculated strength is quite near enough for practical purposes and has the advantage 
of being based on simple assumptions. The foregoing remarks apply to the leg riveted 
in the shop to the beam web. 

In calculating a twisting moment it has been assumed that the outstanding leg 
•of the connection is freely supported at the root of the angle and that the rivets or 
bolts through the outstanding leg are not subjected to tension. Rivets are however 
not supposed to be calculated to resist tension, and further the back-set to these 
rivets is so great that the angle will deform before any material tension is developed 
in the rivets or bolts. 

Where only one connection is used on one side only, the rivets in the outstanding 
leg will be subjected to twisting shear as well as the leg riveted to the web of the beam, 
and must be calculated in the same manner. Where two connection angles are used 
the twisting moment in rivets in the outstanding leg may be assumed for practical 
purposes as balanced. 

Riveting. — The remarks for pillar riveting apply also to girders. The pitch 
near the end should be smaller than the pitch on the centre. In good work, and 
for conditions applicable to the usual calculations, it is of course necessary that the 
proper pitch and distance between rivet lines (set) should be properly arranged. The 
minimum and maximum rivet pitch for certain size of rivets and certain thickness 
of plates should be specified, and the placing of rivets in a girder will also, of course, 
have to be made suitable to transmit the flange stress. Where local loads are applied, 
the shear on rivet due to such load must be calculated when computing the rivet 
spacing for bending. The inset for riv^et or the edge distance for the plate is of great 
■importance. 

The following are suggested as suitable stresses : — 

Single Shear. 

Rivets (shop) ......... 12 kips 

Rivets and turned bolts (field) . . . . . . 10 ,, 

Rough bolts (field) « . . . 8 ,, 

.300 



[&^?.fyE"ES[}.^^ STRESSES IN STEELWORK. 



Bearing. 

Rivets (enclosed) ........ 30 kips 

Rivets (one side) . . • . . . . . 24 ,, 

Rivets and turned bolts (field) . . . . . . 20 ,, 

Rough bolts (field) 16 ,, 

Before concluding, I would again like to refer to the advantage of using pounds- 
in the calculations for steelwork in place of tons, cwts. and lb. The pound is a better 
unit than cwts. for small loads, such as superimposed loads on floors, the weight of 
the floor itself, and the small additions or deductions to the total load which have to 
be made on account of different construction of materials used. For instance, if the 
superimposed load is 100 lb. per square foot, and the floor finishing weighs 25. 
lb. per square foot, the floor 40 lb., and the beam casings and steel beams, etc., 
average in weight 50 lb., the sum of which is the total load to be used for the calcu- 
lations of the beams and girders, it is obviously more convenient to calculate in 
pounds, than in cwts. and fractions of cwts. I may instance a case where a pound 
is simple to use for calculating the weight of concrete. The weight of a concrete beam 
is approximately i lb. per square inch of sectional area per foot run, assuming the 
concrete weighs 144 lb. per cubic foot. The weight of a concrete slab on the same 
basis is 12 lb. per square foot per inch of thickness. Steel weighs 3-4 lb. per square 
inch per foot run, etc. 

I would also hke to refer to the method of taking out loads and recording them in 
the calculations. Simplicity and system, to my mind, are of the greatest importance 
in order to obtain accuracy and speed for big jobs. 

DISCUSSION. 

Mr. W. J. H. Leverton, Licentiate R.I.B.A., asked for information upon the latest practice with, 
regard to the factor of safety. For a long time one-fourth had been taken, but at present, when 
materials and labour are so expensive, it is necessary, for the sake of economy, to sail as near to the 
wind as possible, and generally the advice given is to take one-third. With regard to the stress on 
steel joists embedded in concrete, the author had spoken of stressing them up to 20 kips, which, in 
round figures, was about 9 tons, and of the strength which was gained by the lateral support which 
the concrete gave. Is that 20 kips, or 9 tons, Hmited to the compression of the flange or does it include 
the tension of the flange as well, because although the joist is strengthened by the concrete as regards 
compression, it gains no strength in tension, unless, of course, the slab of concrete is very much deeper 
than the joist itself. 

Mr. E. Lawrence Hall, referring to the stress in the upper flange of a girder or joist, said if that 
had any length of span certainly a less stress should be put into it than the ordinary standard stress, 
but the L.C.C. regulations are silent on that subject, and when these are revised something ought to 
come in in this connection. 

Mr. Gordon Young, M.C.I., referring to gusset plates to the stanchions, asked the author's opinion 
as to allowing sufficient rivets to take up the whole of the stress on the stanchions. Some engineers 
consider that if the gusset plates and angles are riveted on and then the hinges planed, and if the 
workmanship is good, it should not be altogether necessary to provide the full number of rivets as 
required bv the calculations. He also asked for some information regarding lattice stanchions. He 
believed that Mr. Bylander, in Selfridge's building, had advocated the use of chaimels with lattice 
bars on the upper lengths, in order to keep the section the same throughout the entire length of the 
stanchion. It is somewhat difficult to say the amount of stiffness one should use, especially in very 
deep lattice girders where the loads are not excessive. 

Mr. Allan Graham, A.R.I.B.A., said that shop drawings made a very great difference, not only 
with regard to the carrying out of the work, but as regards cost. When everything was being done 
to reduce costs we cannot reallv afford to take too much account of secondary stresses. With regard 
to Mr. Leverton 's remarks as to the tension of the bottom flange, he did not think tension came 
into consideration. When dealing with beams embedded in concrete, it is very useful to be able to 
look up the L.C.C. tables, find out the length and find the stress. The author had also said m the 
paper that the bending stress should not be added to the stress due to flexure for a very slender 
pillar in order to ascertain the total stress. Here again the speaker was prepared to stick to the L.C.C. 
tables, unless he found that Mr. Bylander's would give better results. 

Mr. Lawson S. White, A.M.C.I., asked the author's opinion as to the desirability of standardising 
clearances of rivets. With regard to eccentric loading on columns, if a girder were carried by two 
brackets, one on each flange of the stanchion, so that the girder would bear on both, would the stanchion 
be considered eccentrically loaded in the plane of the axis of the beam? Would the rivets in the 
bracket nearer the centre of the girder be more heavily stressed than those m the further bracket ? 

Mr. A. E. Marshall, M.C.I., referring to the question of rough bolts, asked Mr. Bylander to say 
what lie allowed In \)c ildiir in luactice in the case of rough bolts, whether he allowed that any ordinary 
bolt (ould be used, because the usual bolts supplied would be threaded very often fomearly the whole 
length of the shank. Would he specify that rough bolts should have less thread, and should be accom- 
panied by a washer, so that the ends could be screwed up ? 

301 



5. BYLANDER. [CQSICKETE 



The President, speaking with regard to clearances, said that for years the linginccriiig Standards 
Committee had from time to time discussed the question, and there was a division of opinion as to 
whether the bolts should be standard or the hole. When that controversy was settled the rest would 
easily follow. There were one or two parts of the paper where it might be advantageous to make some 
correction. The question of the standard of stability would require long and careful consideration. 
Suggestions have been put forward which would be considered by many engineers and time alone 
would tell the extent to which they had been adopted. As to the paper itself, tiie author said on page 
3 that the unit of weight which he referred to as a kip was legalised in Great Britain by Act of Parlia- 
ment, but under a different term, namely the " millal." The speaker was not quite sure, but he 
believed that about May, 1907, he himself made the suggestion that 1,000 lb. should be used as a 
unit,«is it was found to be convenient in reinforced concrete work. The " cental," 100 lb., was legal- 
ised by Act of Parliament in 1878. Prior to that date there were many standards of cwts. in use by 
different nationalities,- and it was thought desirable to have a new standard. Therefore, the cental 
was legalised, but prejudice had been much too strong and the cwt. of 112 lb. still persisted in this 
country. He, therefore, introduced the unit of 1,000 lb., and gave it the name millal. Those who 
had to make calculations would desire to use a unit whicli would result in small numerals, and the 
use of the unit of r, 000 lb. was a means of avoiding large numerals. In the paper Mr. Bylander had 
suggested the word "sets" instead of " pitches," but the speaker preferred the term " mid-set " 
rather than " angle-set." 

THE LECTURER'S REPLY. 

Mr. Bylander, in replying to the discussion, said he ratlier feared they would not adopt the lb. as 
a miit because the figures would be too big. Mr. Leverton had referred to the factor of safety, but he 
was not prepared to suggest whether it should be one-third or one-fourth. A definite rule as to stresses 
and as to the factor of safety to be adopted was very uncertain, and he thought it better not to lay 
down hard and fast rules. The paper set out to explain that it was not so much a question of theory 
as to what stress was used, but rather a question of the conditions. It should be left to the engineer 
to fix the exact stress, but the factor generally adopted, namely, one-fourth, was the wisest thing. 
Dozens of tests had been made on full-sized columns, and it was interesting to notice that a steel which 
would stand 60,000 to 70,000 lb. per square inch tensile would only stand about 35,000 lb. compression. 
Under the best conditions a factor of safety of one-third should be adopted, and an even greater one if 
friction be taken into account. With regard to the stresses in steel, he was not very much in favour 
of calculating that the concrete would act as a compression iiange or that beams embedded in concrete 
would act as reinforced concrete. If it were desired to take advantage of the concrete as a compression 
member it would be better to use bars and to do away with the steel at the top altogether. His reply 
to the question would be that he referred to the stress in the bottom flange as well as the top flange. 
Referring to the question of the gusset plates on pillars, his own suggestion was that there should be 
no limit at all as to the number of rivets to be placed in the gusset plate ; there should be no fixed 
rule that the rivets in the gusset plates should be a certain percentage. It should be dependent on 
conditions. A point to be emphasised, however, is that at the end of a pillar, either at the joint or at 
its base, it is advisable not to stress each individual thickness of plate in the main section of the pillar 
to the same extent as in the pillar itself, because at the end the plates are not firmly held together. 
With regard to using lattice colunms, in selecting the sections of colunms, as well as other sections, 
market conditions must be taken into account. With regard to the stiffness on plate girders, Mr. 
Bylander did not know of any definite rule or any simple method by which the section of the stiiiener 
or the position of the stiffener could be determined, except, that as a rough rule, they must have a 
stiffener when the height of the girder exceeded 60 times the thickness of the web. As to Mr. Graham's 
remarks, he agreed it was no good applying beautiful theories if they could not produce the buildings 
their clients would pay for. The cost was very important, but should not be the first consideration ; 
safety should be considered first, and therefore it was useful to have some standard to go by such as 
had now been laid down by the authorities in most of the large cities. Regarding the reference in the 
paper to flexure and bending stress, what was meant was that if, say, a slender pillar were calculated, 
with slendemess up to 140 or 200, for a certain ratio, and there was a bracket, say, on the floor level, 
carrying crane work, and the maximum stress permissible was obtained at the free end, or if fixed, at 
both ends, the bending stress or flexural stress would occur at the top of the pillar, and there was very 
little stress due to what he incorrectly called flexure. Inflection wouFd perhaps be better. What 
was meant by flexure was the bending stress due to slendemess, and bending stress should be the 
flexural stress due to eccentric loading. Mr. Lawson White had referred to the question of clearances. 
As far as he could understand, the general practice was that the diameter of rivets should be referred 
to as nominal. When they referred to a J in. diameter rivet it was neither the diameter of the rivet 
nor the diameter of the hole, because a great number of firms and shops adopted the practice of using 
a rivet which was less in diameter than the nominal, and therefore when the diameter of a rivet was 
specified it should be the diameter of the rivet before driving. As to the diameter of the hole that 
meant the finished hole after drilling. Clearances are not at all standardised. The limit generally 
adopted is -is in. between the actual diameter of the rivet before driving and the actual diameter of 
the hole after drilling. Unfortunately, a good many firms adopt a clearance of \ in., but in very 
few cases would the rivet fill the hole completely if such clearances were used. As to the question of 
whether the brackets on two sides of a column were equally stressed in supporting a beam running 
at the side of it, that was a question of engineering judgment. It is very bad practice to assume that 
one beam can have two individual bearings, and that the load can be calculated in any particular 
ratio. If one bracket were a little lower than the other, one was taking the whole of the load. With 
regard to bolts, under no circumstances must bolts be used with the whole length threaded. Ordinary 
bolts are very unreliable. At the same time, in heavy work the turned and fitted bolt is more reliable 
than the rivet. He agreed with the President's remarks as to the words kips and millals. The sug- 
gestion that mid-set should be used instead of angle-set was also a good one, and he himself would be 
■quite ready to adopt it. 

302 



To- CXJNSTBUCnONAll 



CONCRETE COTTAGE BUILDING. 




CONCRETE COTTAGE 
BUILDING. 



^^S 



NORWICH HOUSING SCHEME. 

To whatever part of the country one turns, concrete cottages are to be found. 
It would really seem that eventually the advantages of this method of construction 
are being appreciated, and that those who have worked so persistently in over- 
coming apathy and prejudice are at last feeling that they have not, after all, 
been sowing on barren soil. Of late an additional impetus has been given to 
concrete cottage building by reason of the lack of skilled labour, and at Norwich, 
whose rates rank among the highest in England, it is particularly essential 
that the Corporation should exercise every means within its power to produce 
cheap houses. 

Despite the high rates the Norwich City Council have embarked upon an 
ambitious programme, which includes the acquisition of some 416 acres, and the 
erection of 1,200 houses. The first site to be developed was the Angel Road 
site, a layout plan of which is shown in Fig. 1. It wiU be seen that the develop- 
ment is on thoroughly up-to-date lines, the houses being generously spaced and 
pleasantly ranged round closes and cul-de-sacs, instead of being huddled cheek 
by jowl. If there is nothing else for which the country should be grateful to the 
Government in the matter of housing, there is at least this : the fact that they are 
largely responsible, through their technical officers, for inculcating new ideas in 
estate development. 

Although there is no marked shortage of bricks at Norwich, many of the 
houses are being built in concrete on the Angel Estate, a Winget Standard Block- 
making machine being used. On the Mile Cross Estate 100 houses are to be 
built on the Dorlonco System, a system of steel frame and expanded metal. The 
Duo-Slab method, which was fully described in this journal in connection with 
the Leeds Housing Scheme, is also to be employed ; likewise the Calway. The 
houses made with the Winget blocks, eight of which were included in the first 
twelve which were opened by the Lord Mayor of Norwich on October 20th, 1920, are 
built with a 42-in. inner and outer skin and a 2-in. cavity. On certain houses 
these concrete blocks are used to form a plinth and for quoins. The ground 
floors of these houses are of concrete and the upper floors are of timber. The 
houses are roofed with pantiles, a very pleasant roof covering, where there is 
little cutting, and one which enables a low pitch to be maintained, thus economising 
in roof timbers. The chimney stacks are built of Norwich bricks, while the 
breasts and party walls are of Flettons. The sculleries are pointed and lime- 
washed, the other rooms being plastered and distempered. All internal joinery, 
with the exception of the window frames, is treated with Solignum, the window 

303 



CONCRETE COTTAGE BUILDING. 



[QQNCRETEJ 



frames, both internally and externally, are painted white. The houses are lit 
by electricity, the distribution being by means of overhead cables attached to 
the chimneys. The service cable is brought down the chimney in a specially 
constructed duct built into the stack. 

The question of communal heating received consideration, but unfortunately 
the grave necessity of keeping down capital expenditure rendered the outlay 




Fig. I. Layout Plan, Angel Estate. 

which such a service would entail, impossible. The whole of the work on the 
Angel Estate, including the making of new roads, laying sewers, the erection of 
fences, etc., and the houses, is being carried out by direct labour through the 
City Engineer's Department, Mr. Town, the deputy city architect, being im- 
mediately responsible to the City Engineer, Mr. Arthur E. Collins, M.LC.E. 
Professor Adshead, F.R.LB.A., is the consulting architect for the whole of the 
Corporation housing schemes. The amount agreed to by the Ministry of Health, 
on April 15th, 1920, was £850 per house. On May ist, however, it will be remem- 

304 



[j. CONSTKUCTICJMA 
L^EJVGTNEERING 



g 



CONCRETE COTTAGE BUILDING. 



bered that there was a general increase in the rates of labour in the building 
industry, the price of materials also rose considerably, although there has been a 
subsequent welcome fall in certain of them. 




A Pair of Completed Houses, Front View. 
Norwich Housing Scheme. 













w 


■ III 

■ III 


k 


■•II II 
■ill II 
■III II 




.TT 


■III 
■III 
•III 


i^MH 


1 






A 


i 


mti 


'♦;wF 




Norwich Horsiso Schkmi;. 



Fig. 2 shows a finished pair of semi-detached houses built with W'inget blocks. 
Although the elevation is simple, it is extremely pleasant. The windows and 
doors are well proportioned, and the overhanging eaves throw a bold shadow 
which overcomes the bareness so often apparent in houses of this kind where 

D ■ 305 



CONCRETE COTTAGE BUILDING. 



JCDNCBErrEJ 




1 






< 

1' 




3j' 


J1 


3,1 


■. , 


is 

i'' 


— 1 




1 


1-1 


— [I 1 


a| 


' 







\A 



cansrrQVcr\asA 

EMGTNEERING 



3 



CONCRETE COTTAGE BUILDING. 




X en 






s 








4 c^ 



* si 



I) 2 




307 



CONCRETE COTTAGE BUILDING. 



[CDNCRETEJ 



there is no cornice and only a small projection of eaves. The contrast between the 
grey walls and the red pantile roofs is very satisfactory. Fig. 3 is a back view of 
a similar pair. The overhead electric light cables can be seen attached to their 
insulators on the middle chimney stack. Fig. 6 is a corner block, one of the 
hrst to be completed and occupied. It will be seen that the house on the left is 
of brick-work. The effect on this site is mostly obtained by grouping, and by 
variation of material. It shows, in fact, how a unit, simple in itself, if properly 
used, can produce a whole which appears neither monotonous nor parsimonious. 
A plan of the pair of cottages is shown in Fig. 4. The planning is direct and 
straightforward, yet everything has received proper consideration. In the scullery 
there is space for copper, gas cooker and mangle ; pram space is provided under 
the stairs and the two chief bedrooms have wardrobe cupboards. The elevations 
show an alternative of concrete blocks, or of walls built with the lower part of 
in situ concrete, on the Calway system (two 4I in. skins and a 2 in. cavity), or 
facing bricks, and the upper part of 9 in. brickwork rough-coated. Fig. 5 shows 
plans, elevations and section of a block of four with a central passage. Both 
types of houses are of the parlour type, and the rooms are of generous proportions. 
Norwich has been active in raising money by local Housing Bonds. Already 
before the close of last year over ^^92,000 had been obtained by this means, and 
£200,000 by other sources, towards the cost of the housing scheme. It is not 
the intention of the Corporation to carry out all their work by direct labour, 
and on the Mile-Cross Estate a contract has been let to Messrs. Fasey & Co., Ltd., 
of Leytonstone, for the erection of the 100 " Dorlonco " houses. It will be 
appreciated from what has been said that Norwich constitutes one of those 
interesting schemes where brickwork and concrete may be compared side by side, 
not only that, but one system of concrete may be compared with another. In 
this way faults can be noted and improvements made. 




Fig. 6. A Corner Block. 
Norwich Housing Sche.me. 



308 



[^v£^?j^^r^^ CONCRETE HOUSES BUILT AT FOLKESTONE, 1870. 



SOME CONCRETE HOUSES BUILT AT 
FOLKESTONE IN 1870. 

By W. H. POPE, M.R.S.A. 

The Marine Crescent, Folkestone, is situated facing the sea on the Lower Promenade, 
and near to the Pleasure Pier. It was designed and built by John Pope & Son, 
Architects and Builders of that town. 

The Crescent consists of fourteen houses, the houses at each end being much larger 
than the rest. As is seen from the illustration the houses are arranged in the form of 
the arc of a circle, each house radiating to a common centre. 

The erection of the houses was commenced in the year 1870, and they were 
finished by another builder a few years later. It is claimed that this is the first instance 
in which Portland cement concrete was used in this country, or in any other, for the 
erection of dwelling houses, and as such it stands out as an excellent example of 
concrete work even at the present day. 

Each house has bay windows on four floors, the windows on the fifth floor and in 
the mansard roof being set back to the straight line as drawn on plan. This projec- 
tion from the line of the elevation naturally caused more work in arranging the 
iron shuttering, but the result was a more pleasing front and larger and pleasanter 
rooms. At the time of erection the Crescent naturally attracted much attention and 
comment, some of the local papers describing them as " mud houses which they 
thought were very unique." The houses have proved warmer and drier than a brick 
house. They also possess greater stability, the walls being practically one solid 
block, and they do not rock under the influence of heavy gales as most brick houses 
do in exposed situations. 

The method of erection was by means of iron shuttering with angle iron riveted 
around the edges and across the centre to stiffen the plates and keep them from 
getting out of shape ; the side angle iron had a hole drilled in each corner to receive a 
f-in. bolt and nut by means of which it was fixed to uprights or standards which were 
shaped on section 3 sides of a square Fl, having a series of holes in the sides to receive 
the f-in. bolt by v/hich to fasten the shuttering. The shuttering was raised as the work 
of filling in the concrete progressed. The standards were 10 ft. long, which was equal 
to the height from one floor to the top of the joists on the next floor — this enabled 
the concrete to be filled in up to the level of the next floor, the last layer of concrete 
having embedded in it a series of rough boxes to receive the ends of the joists which 
stretched from party wall to party wall. 

The shuttering was then, together with the standards, taken away and re-erected 
on the next floor joists after they had been placed in position. 

The partitions of the rooms were formed in a similar manner, of concrete, but 6 in. 
in thickness ; these were carried up through four floors in order to make fhe rooms 
more sound-proof and substantial. 

The window frames and outer door frames were placed in their positions, wood 
blocks being inserted in the concrete to which they could be fixed later. Sufficient 
shuttering was used to form the walls right round each house, and the concrete was 
allowed two days to set before the shuttering was removed and re-erected. It was 
possible to erect to a height of 2 ft. 6 in. of wall at a time. 

The shuttering for the Bay windows was made in sections, the window frames 
being placed in position and the reveals of the openings formed by boarding, cross 
strengthened to retain the concrete ; these were afterwards taken away and used 
again. Wooden bricks 4" x 2" were embedded in the concrete to receive the door 
jambs, and in side wails to which the staircase stringing was afterwards fixed. At 
a later date when it was found that a breeze concrete brick would allow of a nail 
being driven into it these were substituted for wood. 

309 



ir. H. POPE, M.R.S.A 



[CONCBErE] 



The main walls were 14 in. in thickness and were made of Portland cement con- 
crete in the proportions of i : i : 9 (or nine parts shingle, i part sharp sand and one 
bag cement). These ingredients were shot upon a banker and turned over and 
tlioroughly mixed dry before the water was added. 

The walls were solid and packed or filled with hard blocks of chalk, as fcjllows : — 




CoxcRETE Houses, Marine Crescent, Folkesto.se. 

When the shuttering was fixed and ready to receive the concrete, this was filled in to 
a depth of 3 in., and upon this layer lumps of chalk or burr (a very coarse rock) about 
the size of a loaf of bread were placed. IMore concrete was then filled in and carefully 
worked around the blocks to insure of there being no cavities. When the chalk 
was covered with about 2 in. of concrete, more chalk blocks were inserted and the 
above procedure repeated right up the height of about 60 feet. The surface was 
finally rendered with cement and sand in the usual way. 

The front and back steps were also formed of cement and are in the same condition 
to-day as when made fifty years ago. 

There was also formed at the same period a flight of about 150 steps leading up 
the cliff ; these have been in constant use by visitors to the town, and are still in 
excellent condition and show no signs of wear. 



MEMORANDUM. 

Concreting River Banks. — A useful method of dealing with river banks subject 
to being broken away is to take equal proportions of sand and shingle in a dry state 
and to each six parts add from half to one part Portland cement, thoroughly mixing 
the stuff. This is then filled into rather open textured bags, sewing up the ends so 
that they shall be fairly square, and the bags are laid as a wall in close order so that 
the joints between the bags are coursed as in brickwork. The land side is filled in 
with any kind of soil to give a sound backing, and then, as the water gets into the 
material in the sacks, the cement hardens and a good and durable wall is formed, which 
increases in strength for some time. There is always a part of the material which 
exudes through the bags and cements the whole mass together ; this, of course, assist- 
ing in the maintenance of a sound wall where there is no traffic. The top or coping 
layer of bags should be filled with a better quality of concrete so that it will stand 
against wear. A great point also is to keep the surface of the backing well level or 
slightly above the level of the top of the bags, as on this a great deal of reduction 
of breakage of the wall depends. — Practical Engineer. 



310 



E 



, constbuctional; 
engtneering — ; 



ISIEW METHODS OF CONCRETE CONSTRUCTION. 



NEW METHODS RELATING TO CONCRETE 
CONSTRUCTION. 

The following inieresting particulars dea^ ivilli inrenlions devised by officers 
of (he London County Council and relate to improrrd methods of concrete con- 
struction applicable to cottages, etc. We are enabled, to publish these notes by the 
courtesy of Sir James Bird, Clerk to the London County Council. — Ed. 



Invention No. i. 
This invention relates to ties for cavity walls and is particularly intended for 
application to cavity walls built of concrete. 

The tie constructed in accordance with this invention is formed of concrete, 
cement, or similar moulded material adapted to resist both tensile and compressive 
forces, and is so shaped as to engage with the shells of the cavity-wall in such a manner 
as to resist both separation and approach of said shells. 

The improved tie is preferably reinforced by metal reinforcement and is prefer- 
ably so shaped as to deflect on to the outer wall moisture collecting on its upper surface, 
and to prevent moisture reaching the ties from the inner surface of the outer slab 
from running across the tie. The tie is also preferably provided with a substantially 
central drip edge on the lower surface. 

The accompanying drawings illustrate the preferred form of the invention. 
Fig I. represents a sectional side elevation of a cavity wall showing one of the 
ties in position. 

Fig. 3 shows a sectional elevation of one of the ties. The cavity wall shown is 
formed of outer slabs or blocks O and inner slabs or blocks / which are built up so as 
to provide a cavity C between them. 

The outer slabs in walls of this type 
are conveniently formed of hard concrete, 
while the inner slabs are formed of soft 
concrete. 

It should be understood that the 
improved ties may be employed in cavity 
walls cast in situ ; in this case the pre- 
formed ties are preferably cast into the 
concrete during the operation of pouring. 
The ties T are formed of concrete 
reinforced with metal reinforcement R 
and are provided with dove-tailed ends 
D which engage similarly shaped recesses 
r formed in the slabs. These recesses are 
preferably provided in the meeting edges 
of the slabs and extend from the top to 
approximately half the depth thereof. 

The upper surface of the tie is formed 
with a nose ii of tetrahedral form ; the 
purpose of this nose is to deflect towards 
tlie outer wall any water or other matter 
that may fall on it, and to prevent, so 
far as possible, any moisture which may 
run down the inner surface of the outer 
wall from creeping across the tie. 

The under surface of the tie is formed 
with a drip edge d to cause moisture 
coming on to the tie to be directed to 
tlie centre of the cavity. 

The invention may be summarised 
as follows :— 

I. For use in cavity walls a pre- 
formed tie constructed of concrete, 
cement or similar moulded material so as 







^^ 



3" 



NEW METHODS OF CONCRETE CONSTRUCTION. [ODNQ^ETE] 

to be capable of resisting both tensile and compressive forces and so sliaped as to 
engage with the shells of the cavity wall in such a manner as to resist botli separa- 
tion and approach of said shells. 

2. The combination with a cavit}' wall built up o( slabs, blocks or the like, pro- 
vided on their inner surfaces with undercut recesses, of tics of concrete, cement or 
similar moulded material provided with ends adapted to co-act with the undercut 
recesses so as to prevent withdrawal of the ties from the slabs, blocks or the like. 

3. The combination with a cavity formed of concrete shells cast in situ of ties 
of concrete cement or similar moulded material provided with ends shaped so as to 
resist the withdrawal of the ties from the concrete. 

4. A wall tie as referred to in paragraph i provided on its upper surface with a 
nose or the like directed downwards towards the outer wall slab, and provided on its 
lower surface with a substantially central drip edge. 

5. A wall tie of concrete, cement or similarly moulded material substantially as 
herein described and illustrated. 

6. A cavity wall provided with outer shells composed of concrete tied together 
with dove-tailed ties of concrete, cement or similar moulded material sub.stantially 
as herein described and showm. 

Invention No. 2. 

This invention relates to cavity walls employed in the construction of buildings and 
the like, and is particularly applicable to such walls when built of concrete or the like. 

Hitherto, such party walls have been constructed mainly of two types, commonly 
known as the " closed cavity " and the other the " open cavity " respectively. The 
" closed cavity " wall has the advantage that it provides good heat-insulation, but 
has an attendant disadvantage in that timber running into the cavity is liable to rot 
because damp which finds its way into the cavity does not always dry out. 

In the " open cavity " wall, gratings or the like are provided for ventilating the 
cavity and drying up any moisture that may occur, but such cavities do not provide 
good heat-insulation. 

The object of the present invention is to provide a form of cavity wall in which 
the heat-insulating qualities are maintained, but in which means are also provided 
for ventilating floor timbers so as to avoid the disadvantage first mentioned. 

The invention accordingly consists in a cavity wall constructed in the following 
manner. Open cavities are provided where floor joists or the like project into the 
wall, the adjoining principal wall areas above and below the floor being formed wath 
closed cavities. 

In the accompanying drawings, which illustrate the preferred embodiment of 
the invention. Fig. i represents a section through the upper portion of the cavity 
wall of a two-storeyed concrete building. 

Fig. 2 represents a continuation of the section below the portion shown in Fig. i. 

Referring now to the drawings. 

Above the foundations F is placed a closing block B ^ upon wdiich the inner and 
outer shells /, O of the wall are built. The upper end of the cavity C^ so formed is 
closed at the level of the sill S by tiles or plates T, and is similarly closed around 
the vertical edges of the window opening by the window frame IV. 

A block or a beam B ^ which also functions as a lintel, completely closes the 
cavity below the level of the floor joists /. 

Above the block B 2 are placed inner and outer wall shells 7^, O^, which are provided 
at intervals with convenient openings indicated in dotted lines, so that the cavity 
C^ between them is ventilated, the air preferably having access also betw^een the floor 
joists /. 

This open cavity C^ is closed by an upper block B ^ ; and the remainder of the 
wall in the upper floor is constructed with a close cavity in the manner described for 
the lower floor. The closing blocks or beam B* acts as a support for the timber of the 
roof R. 

The invention may be summarised as follows : — 

I. A cavity wall in which the joists of a floor projecting into said wall are received 

312 



n 



CONSTKUCnCN. 
ENOTNEERING 



iaD 



NEW METHODS OF CONCRETE CONSTRUCTION. 




in one or more open cavities, the adjoining principal wall areas above and below said 
floor being formed with closed cavities. 

2. A cavity wall in which a principal wall area between successive floors is formed 
with one or more closed cavities, the joists of the said floors being received in open 
cavities. 

3. A cavity wall having closed cavities extending between the separate floors, 
ceilings, or the like and horizontally-extending open cavities at the levels of the said 
floors, ceilings or the like adapted to receive the joists thereof. 

4. A cavity wall for concrete and like buildings substantially as herein described 
and shown. 



Invention No. 3. 

This invention relates to concrete walls and the like and has for its object to 
provide a method of constructing concrete walls in which the advantages of mono- 
lithic construction can be obtained without the usual attendant disadvantage involved 
in the cost of timber or like temporary formwork. 

The method of building concrete walls in accordance with this invention consists 
in first making a cavity wall by aid of concrete blocks, provided on their inside surfaces 
with undercut grooves or other means of secviring adhesion, and then pouring concrete 
into the cavity. 

The poured concrete thus unites with the blocks which first act as temporary 
formwork and then become permanently cast into the complete wall. 

The outer blocks of an external wall are preferably formed of hard concrete and 
the inner blocks of soft concrete. 

The blocks are preferably assembled one course at a time, the concrete being then 
filled to a level approximately to one half the heiglit of the course in question ; in this 
way the horizontal joints become staggered through the wall. 

The outer surfaces are preferably formed with undercut grooves to facilitate keying 
of plaster or rendering. 

In the accompanying drawings wliich illustrate the preferred method of carrying 

313 



NEW METHODS OF CONCRETE CONSTRUCTION. ^CTVCKETE 




r ~ " ~ — ^ 




1 
1 



ry2. 




the invention into effect, Fig. i shows a section through the lower portion of a wall 
constructed in accordance with the invention. 

Fig. 2 shows an elevation of a portion of the wall prior to plastering or rendering. 

Fig. 3 shows a sectional plan of a portion of the wall. 

Referring now to the drawing, inner and outer blocks or slabs /, O are first erected 
upon a damp course block D. These blocks are provided on their horizontal surfaces 
with co-acting ridges and grooves G to facilitate assembly and to assist in preventing 
ingress of damp through the joints. 

A single course of these blocks I, O is preferably first erected and concrete C is then 
poured into the cavity to a height approximating to one half of the height of the blocks 
as indicated in dotted lines. Another course of blocks is then laid and concrete is 
poured into the cavity up to a level approximately half way up the second course of 
blocks and so on until the wall is completed, the topmost course being completely filled 
in with the poured concrete. 

The blocks or slabs /, O are provided on their inner and outer surfaces with dove- 
tailed grooves G. The grooves on the inner surfaces act as keys for the cast concrete 
and the grooves on the outer surfaces act as keys for rendering R and plaster P respect- 
ively. 

The particular form of block which it is preferred to use for this purpose is that 
described in Invention No. 4. 

The invention may be summarised as follows : — 

1. A method of constructing concrete and like walls consisting in forming 
inner and outer shells of similar moulded blocks and slabs, provided on their inner 
surfaces with means for securing adhesion to concrete, and in casting concrete 
between the said inner and outer shells. 

2. The employment as formwork for concrete or like walls of concrete or similar 
blocks or slabs provided on their inner surface with means for securing adhesion to 
concrete, the formwork being permanently cast into the wall. 

3. In a method of constructing concrete and like walls referred to in paragraph 



314 



(&gSX^^S]S?g NEW METHODS OF CONCRETE CONSTRUCTION. 



I, breaking the joint between successive blocks or slabs and successive layers of 
poured concrete substantially as herein described. 

4. Concrete walls constructed in the manner substantially as herein described 
and illustrated. 

The alternative form of the Witan System is devised to meet the following special 
difficulties : — 

(i) The shortage of bricklayers. (2) The shortage of plasterers. (3) The cold- 
ness of rooms having open cavity walls. {4) The liability to dry rot in the floors 
of rooms having closed cavity walls. (5) The insanitary condition of walls having 
cavities in communication with the space between the floor boards of the upper storey 
and the ceiling of the ground storey. 

The effect of roughcasting is obtained by inserting cocoa-nut fibre matting in 
the shuttering, and removing the matting after the concrete has hardened sufficiently. 

Hitherto cavity walls have been constructed mainly of two types, commonly 
known as the " closed cavity " and the " open cavity " respectively. The " closed 
cavity " wall has the advantage that it provides good heat-insulation, but has an 
attendant disadvantage because the timber running into the cavity is liable to rot, 
and the dry rot is liable to spread throughout the whole area of the floor. In the 
" open cavity " wall gratings are provided for ventilating the cavity and drying up 
any moisture that may occur, but such cavities do not provide good heat-insulation. 

The object of the Witan construction is to provide a form of cavity wall in which 
the heat-insulating qualities are maintained, but in which means are also provided for 
ventilating the floor timbers so as to avoid the liability to dry rot. 

The Witan system consists in a cavity wall constructed in the following manner :— 

Open cavities are provided where floor joists project into the walls, and the 
adjoining principal wall areas above and below the floor are formed with closed cavities. 

The through concrete which closes the cavities will also tie the inner and outer 
leaves of the wall when the metal ties shall have rusted away. 

Invention No. 4. 

This invention relates to concrete and like moulded building slabs or blocks 
which are employed for building up walls, partitions and the like. 




/yj 



















r, 














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' 1 










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ri^.4 



315 



NEW METHODS OF CONCRETE CONSTRUCTION. [CDNCRETE] 



Slabs constructed in accordance with this invention are of tlie kind provided on 
each side with grooves for securing adhesion to plaster, concrete or tlie like, the char- 
acteristic feature being that the grooves on one side are so spaced that successive 
courses can be built up so as to break vertical joint and to form continuous vertical 
grooves in the wall. 

In the accompanying drawings which illustrate the preferred form of the inven- 
tion : — 

Fig. I represents a plan of an improved slab. Fig. 2 represents an elevation 
thereof. Fig. 3 represents a side view thereof. Fig. 4 represents to smaller scale a 
wall or partition built up of the slabs. 

Referring to these drawings, the slab S is formed on its two faces with undercut 
grooves G which are so spaced that when successive slabs are built up to break joint 
in the manner indicated in Fig. 4, there will be a continuous groove down the slab. 

The slabs are preferably formed on one horizontal face with a central channel C, 
and on the other horizontal face with a co-acting central ridge R. 

If, as is preferred, the grooves G on both sides of the block are exactly similar to 
each other, the slabs can be placed without the necessity of considering which side 
is to form the front and which is to form the back of the slab. 

The invention may be summarised as follows : — 

1. A building slab of concrete or like moulded material provided on both sides 
with grooves for securing adhesion to plaster, concrete or the like characterised 
in that the grooves on one side are so spaced that successive courses can be built 
up so as to break vertical joint and to form continuous vertical grooves in the 
wall. 

2. A building slab referred to in paragraph i in which the grooves on both sides 
are exactly similar to each other so that the faces of the slabs are reversible. 

3. A building slab substantially as herein described and shown. 

Invention No. 5. 

This invention relates to wall-ties which are employed for maintaining at the requi- 
site distance apart the shells of a cavity wall of a building or the like. 

The invention relates more particularly to metal wall-ties in which a coating of 
enamel or the like is provided to protect the tie against corrosion by moisture and the 
Hke. 

Such metal ties are usually made from a metal blank of rectangular section, the 
ends being fishtailed or similarly extended to give a grip in the mortar or concrete of 
the walls in which they are embedded. When such ties are coated with enamel or 
the like there is a tendency for the coating to crack at the sharp edges with the result 
that corrosion takes place. 

In accordance with the present invention, the blanks from which the ties are 
made are formed without sharp edges so that the cracking tendency of the enamel or 
the like is minimised. 

In the accompanying drawings which illustrate the preferred form of the inven- 
tion : — 

Fig. I represents an elevation of a w^all-tie. Fig. 2 represents a plan of the 
same. Fig. 3 represents to enlarged scale the cross-section of the tie taken along 
the hne XX, Fig. 2. 

The tie is formed from a strip a of metal, the edges of which are rounded ; the 
degree of rounding may be varied, but it is preferred that the edges shall form semi- 
circles. 

A twist t is formed in the usual manner in the centre of the tie to assist in over- 
coming the tendency for moisture to creep from one side of the tie to the other. 

The ends e are expanded or fish-tailed ; it is not essential that the edges of these 
ends be rounded because they become embedded in mortar or the like and so are 
protected from the action of moisture. 

The invention may be summarised as follows :— 

I . A wall-tie formed from a metal bar or strip, the cross-section of which possesses 
no sharp edges, for the purpose described. 

316 



E 



CDNSTBUCnONA 
EMGl>ttXRlNG 



1 



NEW METHODS OF CONCRETE CONSTRUCTION. 




Fig. I. 




2. A wall-tie constructed from a metal strip or bar of which the cross-section is 
a rectangle with rounded edges substantially as and for tlie purpose herein described. 

3. An enamelled metal wall-tie substantially as herein described and illustrated. 



MEMORANDUM. 

New Methods of Proportioning Concrete. — New methods of proportioning concrete 
mixtures, and the procedure found satisfactory for carrying them out in the field, 
formed the subject of a discussion at a recent meeting of the Toronto branch of the 
Engineering Institute of Canada, when Mr. R. B. Young, of the Hydro-Electric Power 
Commission of Ontario, described the experimental basis of the new theories, illus- 
trating his remarks with slides. 

Proport 10)1 i)ig for Strength. — Mr. Young explained that the basis of the new theor}^ 
is the idea of proportioning concrete to develop a certain desired minimum strength 
in a specified time. The Hydro-Electric Power Commission has adopted a specification 
based on this rather than on set proportions. Four classes of concrete have been 
established for the regular work of the Commission, as follows, each to develop the 
stipulated strength at an age of 28 days : Class A, 2,500 lb. per sq. in. ; Class B, 2,000 lb. 
persq.in.; Class C, 1,500 lb. per sq. in. ; Class D, 1,000 lb. per sq. in. These correspond 
roughly with the common proportions 1:1^:3, 1:2:4, 1:2^: 5 and i : 3 : <>. 
This plan, it was explained, is much more logical than the specifying of a set mixture, 
because, for example, a i : 2 : 4 mix may under certain conditions give a strength 
as low as 500 lb. per sq. in., and under more favourable conditions a strength of 4,000 
lb. per sq. in., depending upon the consistencv, the materials employed and the methods 
of measuring and mixing. 

Experience has shown that to the man in the field consistency is a more important 
feature than strength, because he does not know the strength required in the concrete 
and is not ciiarged with responsibility for fixing the proportions. 

Consistency. — The Hydro-Electric Power Commission has attempted to pro- 
portion concrete not only for a given strength but for a given consistency. On the 
groundwork laid by E. N. Edwards and Prof. Duff A. Abrams, a method has been 
(leveloped that makes it possible to attain both a stated strength and stated consistency. 

-The principle outlined by Prof. Abrams is that for a certain ratio of cpiantity of 
water to (juantity of cement, the same strength of mixture will be realised, regardless 
of the proportions, provided that the mixture is readily workable. This law is not 
absolute, however, as variations occur due to dilfcrcncos in materials and the relation 
of the fine to coarse aggregate. 

317 



REINFORCED CONCRETE HANGARS. 



[QGNCRETEJ 



REINFORCED CONCRETE HANGARS. 

The use of reinforced concrete hangars for dirigible balloons is extending in Italy. 
Two hangars built by the Societe Porcheddu of Turin and described in the Revue de 
Beton Anne are 386 ft. long, 203 ft. wide and 123 ft. high. The foundations are 
designed to carry a load of only 28 lb. per sq. in. and are embedded to a depth of 
13 to 14 ft. 

The structure consists essentially of 14 pairs of columns at 22 ft. centres, 10 ft. 
by 2 it. 6 in. wide and 63 ft. to the springer, tied together by arches 43 ft. in span. 
On each side of the hangar is a smaller building 170 ft. wide and 20 ft. high used for 
stores and offices. Access to the footways between the pillars, at the heights of 53 
ft. and 109 ft. from the ground, is given by three stairways of reinforced concrete. 



^..5g^R^^^ 





Fig. I. Perspective \'iew oi- Hangar. 



"% ^» «■ ^» 













\'iEw OF Part oi- the Model of the Llxon Hangar. 



The imposing fa9ade carries the double doors, each 93 ft. by 103 ft. and weighing 
200 tons, and also, two water tanks each of 2,000 cub. ft. capacity. 

The central pilaster carries a load of 500 tons and has a bending moment of 19 
ton-feet, the lateral columns a load of 400 tons and a bending moment of 70 ton-feet 
and the centre of the architrave a moment of 370 ton-feet. 

318 



i 



C3N5TPUCTION A L 



REINFORCED CONCRETE HANGARS. 



]\lore than looo workmen were employed at a time, and two pumps had to be kept 
constantly at work on account of the bad soil. The columns were moulded on the 
ground and raised into position as required. 

The size of the structure is realised when it is remembered that each arch is 
equivalent to a very large bridge, but the latter would usually be built with two spans 




Fic. 3. View showing the Arc_de Triomphe in Paris standing beneath the Lucon Hangar. 




Fig. 4. X'erticai. Half Section ok Hangar showing the Scaffolding. 



and that no less than 28 of these arches are required at a height of over sixty feet 
above ground level. 

A hangar recently built at Lucon Vendee, France, for two dirigible balloons and 
described in Le Genie Civil is so huge that the famous Arc de Triomphe in Paris could 
easily stand beneatli it ! The design, by M. A. Loissier, consists of an arcli 176 ft. 
higli internally, 186 ft. externally, 362 ft. wide and 733 ft. long. The reinforcement 
was prepared and the hulk of the concrete was precast, so as to secure a maximum 

319 



REINFORCED CONCRETE HANGARS. [CQNCBETB 

speed of erection. The roof is of Minard tiles each 9 ft. by 6 ft. 8 in. by | in. and are 
made of highly reinforced concrete. The purlins are triangular in section and formed 
by three members united by trellis-like bars so as to be of minimum weight. 

The main arch is of the catenary type, this being regarded as the most suit- 
able for the pressures and loads concerned. Each arc is built of fourteen precast 
reinforced concrete segments, each 33 ft. in length. Longitudinal strength is given 
by means of trellis ties and by triangular diagonal braces to each three arcs. The 
arches were built by means of a series of five columns well tied together horizontally 
and mounted on rollers so that the whole series, with the centreing above, could be 
moved forward as the work advanced. Care was taken to lift two equal segments — 
one at each side of the scaffolding — simultaneously, a loo-ton winch being used for 
this purpose. The keystone segment was placed first and then the others in descend- 
ing order, each being coupled to its neighbour in a simple manner. Special precau- 
tions were taken to prevent injury if a coupling broke. When all the segments had 
been joined each arc formed a flexible chain which automatically assumed the correct 
shape. 

The tiles were fixed as rapidly as possible after the erection of each arc and by 
means of ladders from the centreing it was found possible to lay the tiles without walk- 
ing much on the roof. 

The structure is unusually elegant on account of its shape and thinness. As each 
arc is chain, its shape shows the load at any given point. The pressure due to snow 
is negligible as, on account of the shape of the arch, it can only remain near the top 
and therefore near the strongest part of the structure. Wind resistance is based on 
a pressure of 250 lb. per sq. yd. The design is such that variations of 30^ C. do not 
affect its stability. 



A DAM WALL OF REINFORCED CONCRETE FOR THE 
HASSLACHER WEIR. 

The possible advantages of reinforced concrete over mass concrete in large water- 
engineering enterprises are obvious, but unfortunately the saving due to a much 
smaller weight of materials is more than counterbalanced by the uncertainty as to 
the resistance of the reinforced concrete to internal stresses brought about by change 
in volume, variation in temperature, etc. 

Dr. Rossin claims that the dam wall designed bv him is quite free from secondary 
influences and that similar structures may be designed in accordance with definite 
static formulae. 

The dam-wall consists of an apron or separating wall and a series of single frames 
23 ft. apart which support it, the cross section being roughly the shape of letter A. 
The cross-stiffening of these frames is of very small size on account of the small trans- 
verse forces which they have to resist. They are connected on the water side b^- a 
separating wall of horizontal arches. , 

Above the springer of this wall is an intermediate arch which protects the general 
load-carrying portion and gives the wall proper an harmonic extensibility which 
enables it to undergo longitudinal changes due to variations in temperature, etc., 
without damage. The connections between the main and auxiliary arches are quite 
water-tight and, in addition, the supporting frames are provided with a double frame 
with vertical joints which prevent the whole structure from t\\-isting. 

The main and auxiliary arches are of such a form and size that there are no ten- 
sional stresses exerted by the whole mass of water and there is a loaded bracket at 
the top of the retaining wall which creates a moment opposed to the water pressure 
and so prevents any undue strain on the structure. 

The separating wall also has a horizontal course which stiffens it and the concrete 
frame and prevents the necessity of allowing for any movement in the arch. 

The reinforced concrete frames which support the separating wall lie on two 
distinct foundations, each of which is under an almost central pressure for which 

- Continued on page ^^-j. 

320 



E 



coNyreuc-TioNA i: 

^ ENGTNEEJilNG — . 



CONCRETE RESERVOIRS. 




CIRCULAR CONCRETE 

RESERVOIRS AT 

LEAMINGTON, ONT. 



An jnter&sting example of the use of Concrete for reservoir construction is to be 
found at Lcuniington, Ont., where circular reservoirs were constructed to prcwide 
storage for one miUion imperial gallons of water. Our particulars and illustrations 
are taken from an article hy Edward M. Proctor in the " Canadian Engineer," and 
ice also wish to express our thanks to Mr. Edward M. Proctor for the loan of the 
original photographs for the purposes of reproduction. 



Water for the town of Leamington, Ont., is obtained from springs situated 
about i^ miles from the pump house. The supply is carried through a gravity 
pipe line. As this supply is barely large enough to meet the demands made 
upon the system during the hot weather, some measures had to be taken to 
improve the facilities. Well-pumping was tried, but did not prove very suc- 
cessful, and as the fire underwriters were demanding a storage reservoir for lire 

HAZEUTON STREET 




DRAIN 



Fig. I. General Plan of Reservoirs. 



purposes, it was decided to construct a reservoir to provide a storage capacity- 
of one million gallons. 

With a "reservoir of this size it is possible to supply the town for several days 
without depending upon the supply from the wells. Also, in the event of a 
big fire, ample water is available. 

After deciding upon the necessity and the size of the reservoir, the question 
arose as to its location. Tlie gravity head fixed the height to which the water 

E 321 



EDWARD M. PROCTOR. 



rCQNCBETE] 



could be raised in any reservoir, and the elevation of the sewer determined the 
maximum depth ; thus the allowable depth of water was fixed at 9 ft. It was 
first planned to build this reservoir rectangular in shape, with a cross dividing 
wall, but it was found eventually that by constructing two circular reservoirs, 
considerable saving would be effected in the cost of construction in spite of the 
fact that considerably more land would be required. 

The general layout of these reservoirs is shown by the accompanying plan, 
Fig. I. The tanks are 100 ft. in diameter and are located 116 ft. centre to centre. 

The piping arrangement is rather novel, as it permits of either one of the 
basins being operated independently, or both being used in series. They are 




•6-' ,£"■-£-■ 

Fig. 3. Part Section through Reservoir. 



irrr^- 



also so connected that they can be used independently of the old tanks. The 
sewer into which these tanks empty is a large concrete culvert section, which 
had been laid to take the flow of the small stream which formerly flowed along 
the line of the present drain. 

Each tank consists of a floor, a circular wall, interior columns and a 
wooden roof. The columns are 12 by 12 in., concrete, resting on a footing 24 
by 24 in., and each reinforced with four ^-in. steel rods. These columns are in 
two circles, the inner one 30 ft. in diameter and the outer one i8' ft. from the 
inner circle. The roof is of wood, treated with three coats of Barrett's " Car- 
bosota Creosote " paint, and is carried by 2 by 12-in. rafters, bearing on pine 
timbers, which span from column to column. These spans are 15 to 17 ft. The 
centre portion of the roof above the louvre is carried by means of one wooden 

322 



i 



CONSTRUCTIONAL 
EMOITMEERING -^. 



CONCRETE RESERVOIRS. 




Fig. 4. Pouring Floor for Reservoir. 




Fig. 5. Outside Forms and Reinforcing in Place. Inside Forms Ready for Frectiov. 



3^3 



EDWARD M. PROCTOR. 



[CDISCRETEJ 



truss supporting a centre block 12 in. in diameter, to which the joists connect. 
The louvre has a vertical opening of 18 in., and is covered with wire screen to 
keep out birds and insects. Over the entire roof is a four-ply tar and gravel 
cover. The roof has a slope of about 2 ft. 9 in. in 35 ft. 

The floor of the reservoir is constructed in two courses, the lower course 
being 5^ in. of concrete, reinforced both ways with |-in. diameter rods at 12-in. 
centres. On top of this course was mopped two-ply of 8-oz. burlap, swabbed 
on with hot asphalt, all joints being lapped. Above this burlap course was 
laid a 3-in. course of concrete, reinforced both ways with ^-in. rods at 5-in. centres. 
Around all columns a i-in. asphalt joint was constructed, and between this 3-in. 
top laN^er of concrete and the wall, a 2-in. asphalt joint was made. The lower 




iik -.« t ^ 



!.'fi .MkX' 









Fig. 6. View of Concrete Mixer, Hopper and Buggy. 

course was laid directh' upon the soil. The 6 in. of gravel were omitted, the 
reason being that the soil was pure sand, making an excellent foundation. 

As the ground water level was about i ft. above the level of the floor, and 
to avoid any possibility of hydrostatic thrust on the floor when the tanks are 
emptied, a system of drainage w^as installed. This consists of 4-in. field tile at 
i2-ft. centres, connecting into a main 5-in. tile under each tank. A 5-in. vitrified 
tile laid with open joints was laid around the complete circumference, and into 
this were connected the 4-in. cast-iron downspouts from the roof, which were 
eight in number for each basin. 

Perhaps the most interesting part of the design is the circular wall. This 
wall is 12 in. thick and is reinforced circumferentially by means of the following 
rods : Twentv-two i|-in. diameter, near the bottom, spaced from 4 to 6 in. 
apart ; then six i-in. rods at 6-in. spacing ; and the top course, fourteen |-in. rods 
at from 6 to 9-in. centres. These rods are supported on structural steel struts, 

324 



A EMGINEEJglNG — , 



CONCRETE RESERVOIRS. 




3^5 



EDWARD M PROCTOR 



iCQNCRETEJ 



built of two angles, 2\ by 2 by ^ in., connected by batten plates. These supports 
are placed at 8-ft. centres. This circular wall bears on a footing 3 ft. in 
width, which is also circular. The rods in the lower course of the floor projected 
from this footing. The wall is corbelled out at the top to provide for a gutter. 
This wall has no physical connection with the footing. The method of con- 
struction was as follows : The footing was first poured and finished with a trowelled 
surface, upon which was applied a coating of asphalt. The outer forms were 
erected, and then the reinforcing was placed, after which the inner forms were 
placed, and when all was in readiness the concrete for the entire wall was poured 
continuously. The steel takes up the entire circumferential stresses, the concrete 
being simply a covering for the steel and means of containing the water. By 
leaving the wall free at its base, expansion and contraction stresses are eliminated. 
In order to provide assurance that the concrete will not crack when subject to 
full stress, a unit stress in the steel of 4,000 lb. per sq. in. was adopted. This 
unit stress is low enough that the resulting elongation in the steel will not crack 
the concrete. 



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/'Sf^ceT 36 .36" 



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CONC;>ETE 

COMCRE7E 




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Fig. 8. Sfxtion through Floor showing Inlet Pipe. 



In Fig. 8 is shown the method that was used to bring the various inlet and 
outlet pipes through the floor and to waterproof around same. These joints 
were found to be very satisfactory and have been absolutely water-tight. 

Considerable study was given to this design to secure an appearance that 
would be as pleasing as possible. This was necessary because these tanks are 
in the centre of the residential section of the town. 

The concrete used on this work was as follows : For the walls, i : i^ : 3 ; 
the lower 6-in. course of the floor, 1:2:4; footings and columns, 1:2:4. 

The specifications called for 10 per cent, of hydrated lime to be added to 
the concrete ; that is, 10 per cent, by volume of the amount of cement used. 
With this mix a very dense and easily handled mix of concrete was obtained. 

Reinforcing steel of a low grade was permitted on account of the low unit 
stress which was adopted. 

The engineer in charge of this work was J. J. Newman, of Windsor, who is 
town engineer of Leamington. The plans and specifications were prepared by 
James, Loudon & Hertzberg, Ltd., consulting engineers, Toronto. 



326 



r»,a3NSTBUCTli 



1C3NAL1 



CONCRETE IN THEORY AND PRACTICE. 



CONCRETE IN THEORY 
AND PRACTICE. 

A practical section especially written for the assistance of students 
and engineers, and others who are taking up the study of reinforced con- 
Crete, or who are interested in the subject on its educative side, 

REINFORCED CONCRETE SIMPLY EXPLAINED. 

By OSCAR FABER, O.B.E., D.Sc, etc. 

In this series of articles it is proposed to keep explanatioTis so simple as to be 
intelligible to anyone desiring to understand the underlying principles of reinforced 
concrete without wading through a lot of mathematics. The results will be accurate 
and wiU agree with L.C.C. regulations, but will be more easy to understand. The 
articles should also form an excellent introduction to those who will need to follow 
them up with a more advanced work. — Ed. 



CHAPTER VII. 

76. Having now considered the general 
principles of proportioning sand, ballast, 
and cement, we may now consider the 
materials separately, as the production 
of a good concrete depends on selecting 
the best from first to last — not only the 
best materials, but the best combinations, 
treatments, and so on — and this involves 
some knowledge of the various pitfalls 
which lie in wait for the inexperienced. 

77. Cement. — The strength of the con- 
crete depends absolutely on the cement, 
and in reinforced concrete it is essential 
to use the best obtainable. 

Cement is a mixture of chalk and clay 
in the correct proportions, intimately 
mixed, burnt, and ground. 

In some places, notably Belgium, strata 
are found containing chalk and clay in 
roughly the right proportions, and these 
when burnt give a so-called natural 
Portland cement, but as the proportions 
vary a good deal the result is very 
uncertain, owing sometimes to too much 
chalk and sometimes to too much clay in 
the cement. 

Natural cement should never be used 
for reinforced concrete, but only artificial 
Portland cement of the best quality. 

For our present purpose we need not 
discuss the method of manufacture, but 
we must consider a few of the properties 
which are important to the user. 

When cement is mixed with water, 
sufficient to form a thick porridge, it 
gradually begins to set or become solid. 
Now the time taken in setting is very 
important, because after setting has 
begun, any disturbance weakens and may 
(lestroy the finished concrete. We dis- 



tinguish two setting times, the initial and 
the final. 

It must be understood that the setting 
is really a gradual process having no 
well-marked beginning or end, and un- 
doubtedly chemical changes occur before 
the initial and after the final set, so that 
these must be regarded only as arbitrary 
but convenient comparisons of the 
behaviour of different cements, and not 
as denoting any absolute beginning or 
ending. 

The British Standard Specification 
gives the initial set as the time when a 
needle i millimetre square in section, 
loaded with a definite weight, gently 
lowered on to the cement just fails to 
completely penetrate it, and the final 
when it just fails to make an indentation 
on the top surface. 

Cements are divided into quick, medium 
and slow setting, and for the purposes of 
reinforced concrete only slow setting 
should be used, as the others do not in 
practice allow the materials to be properly 
mixed, wheeled, deposited, and worked 
round the steel before setting may begin. 

In testing for setting time, it is im- 
portant to use the correct quantity of 
water and to have the temperature about 
60° F., as the time depends greatly on 
these two factors. The same applies in 
practice with the concrete. A cement 
with a final set of one hour at 60° may 
take many hours to set at 40° F. and may 
set in ten minutes at 100° F. 

Remember tliat when the final set has 
taken place, the strength is practically 
nil and hardening begins. 

This is also a gradual process having no 
real beginning or end, but roughly the 
strength increases uniformly with age 

3^7 



OSCAR FABER. 



[CDNCBETFJ 



for the first seven days and afterwards 
at a gradually reduced rate, and roughly 
will vary as follows : 

7 days looo lb. sq. inch ultimate 

compression 
28 days 1500 ,, ,, ,, 

4 montlis 2250 ,, ,, ,, 

12 months 2500 ,, ,, ,, 

After one year, the strength varies 
little, but seems to rise and fall in a 
peculiar manner which we need not 
concern ourselves with here. 

Consequently, if centering or strutting 
is removed in less than 28 days, remember 
that the concrete has not reached its full 
strength, and should not receive its full 
load unless the design specially provided 
for this. 

Next after setting, the strength of the 
cement is important. 

The British Standard Specification 
provides for specimens i in. square to 
be tested in tension, some neat cement, 
and some 3 to i standard sand to cement, 
both at 7 days and in 28 days. 

Unfortunately the standard required 
is much too low, as manufacturers are 
able to produce a far better cement than 
is needed to pass British Standard, and 
this greater strength results in a stronger 
concrete. 

There is no difficulty to-day in getting 
300 lb. per square inch in 7 days with a 3 
to I sand specimen, and 6501b. per square 
inch in 7 days with iieat cement, although 
British Standard asks for much less. 

Fineness of grinding is very important, 
since a cement obviously has far better 
covering power when ground small. But 
the user need not w^orry .about this if he 
sees that his cement gives good strength 
tests, since it is necessary to get line 
grinding to achieve these high tests 
referred to. It should be remembered 
that fine grinding means considerable 
additional manufacturing cost, but is well 
worth it. 

Aeration of cement, that is, exposing it 
to the air some time prior to use, is 
important because it often contains free 
lime which may spoil the concrete by 
causing heat, cracking, etc., whereas any 
such free lime will be slaked if exposed 
to the air or carbonated, and so rendered 
innocuous. As a rule, cement is supplied 
ready aerated, but occasionally is des- 
patched hot, and should then be spread 

328 



in layers 12 in. thick and turned a few 
times for a week before use. 

Storage. — When small quantities only 
are required, they may be kept in a dry 
warm place in sacks for a few weeks. 

If kept long in sacks, the moisture in 
the air has access to a very large surface, 
and the cement begins to set all round the 
sacks, and suffers in consequence. 

Hence on large jobs, it is better to store 
in bulk, emptying the cement out of the 
.sacks into a cement store, and so exposing 
a lesser surface. This store should have a 
dry floor kept a few feet above the grounrl, 
and walls and roof so made as to keep out 
rain and moist air and free from con- 
densation. Timber and felt is good 
while corrugated iron is bad. 

When cement has been stored long it is 
well to test the setting time again, since 
occasionally the effect of thorough aeration 
is to alter this in a very remarkable 
manner, sometimes in the direction of 
making it very rapid indeed, and some- 
times making it very slow, the deter- 
mining factor being apparently whether 
the air contains carbonic acid or moisture 
to a greater extent. 

78. Sand. — Sand for good concrete 
must be clean and large. Roughly the 
grains should be about jg in. in diameter. 

It is clear that a very fine sand contains 
much more surface in a given volume, and 
therefore needs more cement to cement 
the particles together — or conversely, a 
given proportion cement gives stronger 
mortar with a large sand. 

The importance of cleanliness is very 
great. Frequently the sand as found in 
the pit has a film of loam or clay round 
each particle. This prevents the cement 
adhering, and a very weak concrete may 
result. 

The author has made tests showing 
that a large clean sand mixed 3 to i gave 
about 2,000 in one month, while a clean 
but fine sand, or a large but loamy sand 
gave only 500 or one quarter. In these 
experiments the fine sand was a blown 
sand as the seaside, and the loamy one 
was a red sand from Croydon gravel. 

In both cases the use of such a sand 
would have spelt disaster. 

It used to be specified that the sand 
should be sharp. Later tests, however, 
show that the shape of the particles does 
not matter, and round ones are as good as 
sharp ones, provided they are large and 
clean. 



&£ay.^V'b[Jg>^ BUILDING TRADES EXHIBITION, 1921, OLYMPIA. 









THE BUILDING 

TRADES EXHIBITION, 

1921, 

OLYMPIA. 




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The second post-war Building Trades Exhibition, held at Olympia last month, provided 
much of interest to all concerned with building. Following as it did within twelve 
months of the previous show, it was not to be expected that as many new machines 
and new methods of construction would be on view as last year, when the Exhibition 
embodied much of the results of the inventions made and experience gained during 
the phenomenal years of the war. However, methods and plant that were new, the 
improvements on systems and machines that are already well-known, and the endea- 
vour demonstrated on many of the stands to obtain a better finish and texture to con- 
crete, were of considerable interest, and give hope for both a reduction in cost and an 
improvement in appearance of concrete building in the near future. The adaptability 
of concrete to new purposes was noticeable on many of the stands, such as concrete 
fireplaces and mantels, window sashes, and cisterns and every description of 
rain-water goods in asbestos cement. 

BUILDIXG COXSTRUCTIOX. 

An ingenious new system of concrete construction was exhibited by the Tyiangidar 
Concrete Construction Co. (Imber Court, Thames Ditton), in which a number of trian- 
gular blocks are used of different dimensions, but wherein each size smaller than the 





' Triangular " Block Construction. 



3^9 



BUILDING TRADES EXHIBITION, 1921, OLVMPIA. [(^^jnaFTg 

next largest is in area exactly one-half of the larger. It is obvious that by tlic use of a 
number of nglit-angle isosceles triangles practically any formation can be obtained, 
and that this is so, and that bay windows, buttresses, return ends, columns, etc. can be 
formed without cutting was demon- 



strated by the sections exhibited. 
Where desired, the blocks may be 
made with ballast concrete on the face 
which will be exposed to the weather 
and of porous aggregate on the other 
two sides. To economize in material, 
and to form an air-space in the wall, 
the blocks are made hollow. To 
form a 9-in. wall blocks are used 
measuring 17^ in. along the outer face 
and 8f in. on the other faces laid to 
bond together, return ends and corners 
being formed with blocks of exactly 
half those dimensions. The blocks 
are laid to break joint in each course, 
and vertical air-spaces are thus ob- 
tained throughout the entire height 
of the wall. The blocks are made in 



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132 



A.B.C. SYSTEM 








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" Thewlis " System of Concrete Construction {see p. 331). 

six sizes, from 4I in. along the face to 2 ft., and walls of any thickness can be built 
with them. The Company is in a position to supply quantities of these blocks, or 
machinery for their manufacture. 

The well-known expanded metal reinforcements manufactured by the Self-Senter- 
ing Expanded Metal Works, Ltd. (no, Cannon Street, E.C.4) were displayed to advant- 
age by sections of floors, ceilings, and walls in which the material was incorporated. 
These reinforcements are specially designed to dispense with the use of forms in the 
construction of light concrete structures, and are now being extensively used for that 
purpose. " Self-Sentering " is ribbed expanded metal, especially designed for floor 



330 



I&^?.5g^i^g BUILDING TRADES EXHIBITION, 192 1, OLYMPIA. 

and ceiling construction, and which will retain wet concrete. " Trussit," designed for 
wall construction, is an expanded metal sheet which when covered with two inches of 
cement plaster forms an excellent wall for use in housing schemes. For suspended 
ceilings or partitions, " Herringbone " metal lathing was shown. This material is 
rigid and strong, and only requires studding at 16 in. to 20 in. centres to keep it in place. 
Floors, ceilings and walls built with these materials are sound-proof and fire-resisting,, 
and as the expanded metal remains as an integral part of the structure, all the strength 
of reinforced concrete is obtained without the use of shuttering. They have been 
approved by the ISIinistry of Health for State-aided housing schemes, and are being 
used on such schemes on a large scale. 

A new system of concrete block construction, by which the blocks are interlocked 
by a method of dovetailing, was shown by Mr. J . Thewlis (2, Manor Terrace, Headingley , 
Leeds), an architect. In our illustrations (p. 330), Fig. i shows the setting out of an angle 
to a 9-in. wall ; Fig. 2 is the elevation of Fig. i, showing 24-in. blocks (A), which are 
the standard size, and smaller blocks (B) used to break joint ; Fig. 3 is a section 
through Figs, i and 2, showing the dovetail lock, and the clear air-space throughout 
the wall ; Fig. 4 shows the application of the same block in the construction of an 
i8-in. wall, the block (C) serving to hold the outer and inner walls apart ; if desired. 




" Kino " Pavement Lights. 

the cavities can be filled with concrete and reinforced ; Fig. 5 shows an elevation of 
Fig. 4, with the string course reinforced as a solid beam ; Fig. 6 is a section through 
Figs. 4 and 5, showing the interlocking arrangement. The application of the system 
to details of construction is shown in Figs. 7, 8 and 9. Fig. 7 illustrates a window or 
door head formed of blocks with raking joints ; Fig. 8 shows a square shaft or column ; 
the locking device is employed on opposite sides in alternate courses, thus locking the 
whole against lateral stresses from any direction ; Fig. 9 is a chimney flue designed 
to serve for two adjoining houses. The system has the merit of simplicity, and the 
dovetail joints ensure a rigid construction. 

Some interesting specialities were shown on the stand of Messrs. J . A. King 6- Co. 
(181, Queen Victoria Street, E.C.), who, in addition to solid and hollow concrete blocks 
and slabs, exhibited their reinforced concrete glazing bar as applied to pavement, 
floor, roof and stallboard lights. The glazing bars are strongly reinforced, and possess 
many advantages over the ordinary type ; for example, they improve in strength 
with age, they cannot rust, and the expense of periodical painting is eliminated. They 
are quite pleasing in appearance, and when used for pavement lights are much more 
in harmony with the surrounding pavement than metal glazing bars. A furtlicr 
advantage is that in wet weather they will not tend to become slipper^'. ' 

The Moler Fireproof Brick and Partition Co., Ltd. (Vickers House, Broadway, 
S.W.) demonstrated the various constructional uses of their special brick by sections 
of walling, floors, partitions, etc., and the warm reddish-brown colour had a very 
pleasing effect. In addition to their good appearance, the bricks are remarkably light, 

331 



BUILDING TRADES EXHIBITION, 1921, OLYMTIA. [CDNCTETt T^ 

Avhile they are at the same time of exceptional strength and fireproof. Tlie bricks 
are made botli solid and hollow to standard and other sizes and of any pattern 
for special purposes, and they are also made with various surface finishes. The 
material from which they are made, " Moler," is porous, and when coated with cement 
or other waterproofing material forms a light, strong, waterproof construction, the 
absorbent nature of the interior preventing trouble from condensation. " Moler " is 
a deep-sea deposit of diatome-silex mixed with alumina of which the Company owns 
large deposits of fine quality at the Island of Mors, Denmark. It lias high insulating 
(jualities, and sliould be in considerable demand wliere light yet strong structures 
are required. 

The possibilities of asbestos cement in its various forms, both as a sound material 
for the construction of light buildings and as a material which provides considerable 
scope (or artistic treatment, was admirably demonstrated on the stand of the British 
Fibrocement Works, Ltd. (22, Laurence Pountney Lane, E.C.), the makers of " Fibrent " 
asbestos-cement sheeting, tiles, etc. Two gables were shown to illustrate the uses of 
curved corrugated sheets and scolloped slates. Half-inch sheets fixed direct to tlie 
joists formed a very substantial floor, and several finishing methods were demon- 
strated in the treatment of the interior. 

The British Roofing Co. {150, Southampton Row, W.C.i), demonstrated the uses 
of their " Alligator " brand asbestos cement sheeting and slates in various colours, 
and " Everite " and " Asbestilite " products were exhibited by the British Everil( 
& Asbestilite Works, Ltd. (29, Peter Street, Manchester). The latter firm exhibited 
a selection of rainwater goods, gutters, down-pipes, etc., made of this plastic material, 
and its possibilities were further shown by an asbestos cement water cistern, in light 
grey, which we understand has been approved by the Ministry of Health for use 
in State-aided housing schemes. The cistern is of pleasing colour and shape, and 
costs less than the usual iron cistern. The stand of the British Uralite Co. (1908), 
Ltd. (8, Old Jewry, E.C.2) took the form of a garage carried out in " Asbestone " 
asbestos cement sheeting and tiles. 

Messrs. G. R. Speaker 6- Co. (Eternit House, Stevenage Road, London, S.W.6) 
■exhibited an example of the application of their " Eternit" sheets to the construction 
of one-story buildings on their patent " Trellit " principle. In a few words this con- 
:sists of a light steel framework covered with " Eternit " sheets. The framework 
is assembled at the Company's works in sectional units four feet wide which are 
fastened together in such a way that, for purposes of transport, they may be folded 
up into quite a small space. The framework is made of channel steel, the members 
being 5 in. in depth. To the steel framework wooden strips are attached and to 
these the " Eternit " sheets are fixed, thus forming a wall containing a 5 in. cavity. 

The Climbing Steel Shuttering Co. (515, Queen's Row, Sheffield) exhibited their 
system of shuttering for forming monolithic concrete walls. In this system the gal- 
vanised steel plates which form the shuttering are erected above the dampcourse and 
filled to form the first course of the wall. The plates are held apart top and bottom 
by wires, and when the concrete in the lower course has set the bottom wires are cut and 
the plates lifted outwards and upwards to form the shuttering for the next course, 
the original top wires acting as hinges. This operation is repeated until the desired 
height is reached. As each face o' the plate becomes the inside face alternately in 
its progress up the wall, both sides are made smooth in order to obtain a satisfactory 
finish. 

Several other systems of concrete building which are well known to our readers 
were also demonstrated. 

Messrs. Concrete Dwellings {Parent Company), Ltd. (i, Carteret Street, S.W.i) 
exhibited their method whereby walls are laid in situ by means of a patent mould. 
Messrs. J . Wright &■ Co. (South Western Works, New Maiden, Surrey) demonstrated 
their " Utility " concrete block construction, in which ballast blocks are used for the 
exterior wall and breeze blocks for the interior, the whole being bonded together by 
tongues and grooves. The " Fidler " (" Composite ") method of concrete construc- 
tion was demonstrated by the Composite Concrete Construction Co. (51, Pall INIall, S.W.i). 
The cavity walls are formed of large pre-cast slabs 2 J in. thick, 3 in. apart, laid 

33^ 



/^c^Ngw-ric^Ag BUILDING TRADES EXHIBITION, 1921, OLYMPIA. 



to break joint and held in position by wall-ties. Messrs. Panels, Ltd. (14, Red Lion 
Square, W.C. i) showed two systems, viz., the " P. & P." and the " B. K." The 
"P. & P." system consists of concrete piers spaced at about 3 ft. centres, filled in 
with concrete panels 2 in. thick, spaced 3 in. apart to form a 7 in. cavity wall. The 
" B. K." system is a form of interlocking concrete block construction. 

A patent concrete eaves was shown by the Economic Eaves Co. (9, Southampton 
Street, Bloomsbury, W.C.i). Now that gutters and such materials are so difficult 
to obtain there should be a considerable scope for concrete eaves, which effect a 
considerable saving in rain-water goods, timber, etc. 

The well-known " Ruberoid " roofing and dampcourse materials were demon- 
strated by the Rub'^roid Co., Ltd. (81-3, Knightrider Street, E.C.4) by a series of 
interesting models showing the application of these materials to various types of 
roofs, gutters, flashings, dampcourses, etc. " Ruberoid " is a self-finished bituminous 
material which has been in use for twenty-nine years. It is now supplied m 
two colours in addition to the familiar black, namely, red and green, and the models 
showed the attractive results that may be obtained by the use of these coloured 
coverings. A durable and easily laid acid-proof and damp-proof floor covering was 
shown, particularly suitable for covering concrete floors ; it is manufactured in two 
colours — red and grey. 

MACHIXERV. 

The stands containing machinery were perhaps the most interesting in the Exhibi- 
tion, ranging from small hand block-making machines that can be used with economy 
for the smallest job, or for repair work, to large concrete mixing and placing plant 
that would replace a small army of workmen on a large job. 

On their two stands, the Ransome 
Machinery Co. (1920), Ltd. (14-16, Gros- 
venor Gardens, S.W.i) showed a com- 
prehensive exhibit of contractors' plant. 
The well-known " Ransome " pile driving 
equipment, viz., steel sheet piling, steam 
friction piling winch, and pile helmet for 
concrete piles, was shown, and the " Ran- 
some " hand tip-cart, constructed entirely 
of steel, and made in sections which can 
be readily taken apart and fitted together 
again. Self-contained petrol-driven con- 
crete mixers and tar-macadam mixers 
were also shown. The most interesting 
exhibit on this stand was a large con- 
crete mixing and distributing plant, one 
of the largest such combinations we have 
seen in this country. The mixer is of 
the standard " Ransome " revolving- 
drum type with a batch capacity of 
7I cubic feet, which discharges direct 
into a hopper in a steel framework tower. 
The tower can be of any desired height, 
and the hopper is lifted to the top by 
a power-operated wire rope, where it is 
automatically tipped, and the contents 
discharged into another hopper from 
whence it flows by gravity into the distributing chute. The t)utfit, which is fitted 
for. belt drive, is compactly built and contains many ingenious contrivances that 
will commend themselves to those interested. The combination is, we believe, 
equal to anything of its kind that has been used in America, and the adoption of 
such plant in this country would rapidly repay its first cost on large works. 

Messrs. Millars' Timber S^ Trading Co., Ltd. (Pinner's Hall, E.C.2) exhibited 




Rans(i.mu Portable Combined Mixing, Hoisting 
AND Placing Plant. 



333 



BUILDING TRADES EXHIBITION, 1921, OLYMPIA. [CQNCBFTE ] 



a fine selection of builders' plant and labour-saving machinery, including an all-steel 
derrick, suitable for hand and power operation, a special feature of which is the speed 
with which it can be erected and dismantled ; portable and stationary self-contained 
petrol-driven hoists ; petrol-driven compressors, diaphragm pumps ; electrically- 
driven wood-working machinery ; stone crushers ; and the well-known " Jaeger " mixers. 
Messrs. ^Miliars' supply practically every description of plant used in building construc- 
tion suitable for small or large users, and large numbers of them are in use and giving 
satisfaction in all parts of the world. 

Messrs. Hill cS- Co. (Engineers), Ltd. (York) also had a very fine display of labour- 
saving devices. A working model was shown of the " Sauerman " drag-line excavator, 
by the use of which it is claimed one man can excavate sand or gravel at the rate 
of 1,000 cubic yards per day and dump it into .screens, or where required. The exca- 
vator is of the shovel tj^pe, and is drawn and returned from the point of excavation 
to the top of the hoisting tower by means of a double-drum hoist. On reaching the 
point where the material is to be dumped, the shovel is automatically tipped to 
release the contents. Several portable cranes of novel design were shown for hand 
and power operation. 

A selection of concrete mixers of various 
and a couple of block-making machines, 
shown by Messrs. Slot her t S^ Pitt, 
(11, Victoria Street, S.W.i). For 
users there was the " No. 5 Victoria " 
ixer, which has a batch capacity of one 
' ; vard. This machine is mounted on 
skids and is designed for a belt drive ; 
fitted with a batch discharging hopper 
a tank which automatically regulates 
the amount of water for each 
batch — a valuable feature 
when the necessity for accu- 
rately gauging the water 
content of concrete is borne 
in mind. A self-contained 
mixer with a smaller out- 
put per batch (6 cubic ft.) 
was shown in the " No. o " 
Tiachine, which is mounted 
jn a road wheel truck with 
a 6 h.p. petrol engine on an 
extension of the frame. This 
machine is also fitted with an 
automatic water tank, and has 
a side loader. A machine specially suitable for housing schemes and for small 
users is the " Victoria U.U." This is also a self-contained unit mounted on wheels, 
and can readily be moved about by two men. It is fitted with a 2I h.p. paraffin or 
petrol engine, or, if desired, it can be used as a hand machine by d'isconnecting the 
engine and fitting a pair of handles. This firm also exhibited the " Dri-crete " block- 
making machine, the special feature of which is that in the process of manufacturing 
the block a thin layer of waterproofing material is applied to the face. 

The British Steel Piling Co. (Dock House, Billiter Street, E.C.) exhibited a 
good range of contractors' plant, especially in relation to pile driving. " Universal 
Joist " and " Simplex " steel sheet piling, which possess the important qualities of 
being easily driven and withdrawn, were exhibited in sections. An interesting model 
was shown of a " B.S.P." standard pile-driving frame with a :McKiernan-Terry hammer 
at Avork driving and withdrawang piles in a bed of sand, showing the speed at which 
this apparatus works, and some of the smaller sizes of this type of hammer were 
shown separately. These apparatus may all be hired from the B.S.P. Company, 
if desired. Two sizes of concrete mixers were shown on this stand, the " Zenith " 
and the " Zenith Pup." The former has a capacity of one-quarter yard of material, 

334 




The " ViCTORi.\ H.M." Conxrete Mlxer. 



i 



«5N3TDUCXJIOT<JA 
ENGTNEILRING 



^ BUILDING TRADES EXHIBITION, 1921, OLYMPIA. 



and is fitted with a fixed hopper ; it is arranged for a belt drive, and has an output 
of from 75 to 300 cubic yards per lo-hour day, according to size. The " Zenith 
Pup " ha^ a smaller output (about 38 cubic yards per lo-hour day), and is specially 
designed to meet the requirements of builders and contractors on small jobs ; it is 
an entirely independent unit, driven by a petrol engine mounted with the mixer as 
one unit. 

The efficiency and durability of the concrete machinery of Messrs. Winget, Ltd. 
(Grosvenor Gardens, S.W.i) are well 
known to those who have used them, 
and any new production by this firm 
will be examined with interest. In 
addition to their hand and power block- 
making machines, mixers, elevators, etc., 
they showed at the Exhibition for the 
first time a new hand • block-making 
machine — the " Westminster." This 
machine should be particularly useful 
on small jobs, and onlv requires one 
man for its operation. It can be 
adapted for the manufacture of blocks, 
slabs, or bricks, as follows : Single 
blocks, 18 in. by 9 in. by 4^^ in. ; single 
slabs, 18 in. by 9 in. by 2, 2|, or 3 in. 
thick ; half blocks or slabs (9 in. by 
9 in.) of the same thicknesses two at a 
time ; or six bricks of standard size at 
one operation on one pallet. It is 
strongly constructed on a braced iron 
stand, has few working parts, and can be 
recommended for use where an efficient 
hand-machine is required. The pallets 
are interchangeable with the other 
*' Winget " block-making machines. On 
this stand were also shown some sam- 
ples of coloured concrete walling, some 
of the warm red tones being especially 
attractive. The colouring is applied as 
a slurry after the blocks have partially 
set. 

Messrs. Vickers, Ltd. (Broadway, S.W.i) showed machines for the manufacture 
of concrete slabs, bricks, and tiles. These machines are all light and portable, designed 
for hand operation, and the demonstrations that were given proved that they are 
capable of large outputs. On the slab machine, hollow or solid blocks for partitions, 
walls, or pavings are made with either square or groove-and-tongue joints. On the 
tile machine, waterproof concrete tiles of any colour are produced. The tiles are 
interlocking, and are considerably lighter than clay tiles — 7 cwt. per square of roofing 
as against 12 cwt. The brick-making machine is designed to make concrete bricks 
of standard sizes, but by simple adjustments will produce arch bricks, fioor bricks, 
tiles, etc., without the use of additional apparatus. It is claimed tiiat 2,000 bricks 
per day can be manufactured on this machine. 

A large variety of products for treating and increasing the efficiency and adapta- 
bility of concrete was exhibited by Messrs. Building Products, Ltd. (44-46, King's 
Road, S.W.3.) including the following waterproofing and structural specialities : 

Bareau " waterproofing powder ; " Prufit " waterproofing paste ; " Prufitol 
brick, stone, and stucco waterproofer ; ■' Fillertex " plastic crack and joint filler ; 
and " Fibrad " bituminous dampcoursc. Among the specialities for use in factories were 

Rigifix " bolt hanger sockets and slotted inserts, bv the use of which the expense of 
cutting concrete to take bcll(lri\'cs, maciiinery, etc., is obviated ; guards for tiie pro- 




The " Westminster " Block-making M.\chine. 



333 



BUILDING TRADES EXHIBITION. 1921, OLYMPIA. [QGJNCRETE] 




The '■ Universal " Spraying Machine. 



tection of concrete columns and curbs ; " Ferrolithic " fi()or hardener and dust-proofer ; 
Aqualithic " liquid dustproofer and liardener for existing concrete floors; and 
" Fibrad " three-ply roofing in rolls. There were also shown bar-bending machines, 
mould oil, spraying machines, and drum and can tilters. The " Universal " spray- 
ing machine was also shown, by means of 
which waterproofing liquids can be applied 
to walls of any height with a minimum of 
labour and time. 

Bar-bending machines especially designed 
for shaping reinf(jrcing rods for concrete 
construction were shown by Mr. W . Kennedy 
(Station Works, Warwick Road, West Dray- 
ton). These machines are strongly and 
simply built and light in weight, and 
the presence of one of them on a rein- 
forced concrete job will often prevent vexa-. 
tious delays when rods of the required 
shape are not to hand. The machines were 
shown in three patterns: (i) a machine 
weighing 25 lb. to bend rods up to | in. 
diameter ; (2) a geared machine to bend 
rods up to I in. diameter ; and (3) a 
worm geared machine to bend rods up 
to i| in. diameter. The machines will all 
bend cold bars of the sizes mentioned to 
any given measurement. 

An interesting series of labour-saving 
plant was shown by Messrs. Builders' and 
Contractors' Plant, Ltd. (15, Victoria Street, 
S.W.I ). Two types of the " Exe " hoist 
were erected on the stand, and demonstrated the possibilities of such devices in 
saving labour and speeding-up building construction by the rapid hoisting of materials. 
The hoist can be easily 
erected wherever there is 
existing scaffolding, and in 
this connection the efficiency 
of the " Fircrete " timber clip 
was practically demonstrated. 
The value of the hoist is 
considerably enhanced bv the 
fact that its height can readily 
be increased as the building 
progresses, and by the re- 
volving head which enables 
the platform to be swung 
in at the required height so 
that the barrow may be 
wheeled on at the ground 
level and off at the top 
without extra handling. The 
hoist is fitted with a jib 
for handling bulky loads, and 
an automatic stopping device. Two portable " Roll "concrete mixers were on view, 
each fitted with an oil-engine. These strongly-constructed machines have auto- 
matic loading and water-supply devices. A new concrete block-making machine 
— the " Ama," provided with a spring-regulated mechanical tamper, was shown 
in operation, and also a hand tipping cart and the " Klipit " light steel hand barrow, 
which can be taken to pieces in two minutes and stored in a very small space. 

.^36 




The " Klipit " Steel Barrow. 



n 



CONSTKUCTICSMAL 
EMOnVEEiaiNO — ; 



BUILDING TRADES EXHIBITION, 192 1, OLYMPIA, 



Parker, Winder & Achurch 




Empire " Concrete Mixer. 



The " Australia " concrete block-making machine and the " Tonkin " mixer 
were shown at work on the stand of the Australia Concrete Block Machine Syndicate 
(607, Salisbury House, London Wall, E.C.2). The " Australia " machine is now well 
known as a handy and efficient machine, and turns out blocks at the rate of 350 
T-shaped faced blocks or 450 breeze slabs per day. The " Tonkin " mixer is a new 
product of this Company, and was recently illustrated and described in this Journal. 
Both these machines have an output sufficient for the largest jobs, while their cheap- 
ness in first cost and running costs render them a paying proposition for even the 
smallest contract. They were working under practical conditions at the Exhibition, 
and fully justified the claims put for\vard for them. 

Messrs. Parker, Winder 6- Achurch, Ltd. (Broad Street, Birmingham) showed the 
" Empire " concrete mixer. The engine and drum are mounted on a wooden frame- 
work which permits of the drvim being 
turned so that it will discharge to the 
front or sides. The engine is fitted be- 
hind, and the drive is through two bevel 
gears, one at each end of the vertical 
rod that connects the drum with the 
engine shaft. The drum is easily tilted 
to discharge the contents by means of a 
lever at the side. A very strong screen 
was shown by this firm, which should be 
very free from clogging. 

A useful labour-saving device, the 
" Liner " concrete block-making machine 
and elevator, was shown by the Liner 
Concrete Machinery Co. (Newcastle-upon- 
Tyne). The combination consists of a 

strongly-made and simply-operated mould and an elevator mounted on rails, by 
means of which the finished blocks or slabs are transported direct from the mould to 
the curing ground without being handled. The mould is 6 ft. long by 13 in. wide 
by 10 in. high, and wall turn out slabs of this size for lintels, etc., or can be divided 
into any number of smaller compartments for the manufacture of blocks, quoins, etc. 
On large contracts the combination should result in a considerable economy in 
labour being effected. 

Various block-making machines, adapted for forming any shape of block, coping, 
channelling, etc., either solid or hollow, were shown by the Martin-Harvey Engineering 
Co. (116, Victoria Street, Westminster, S.W.i). The Manelite Patent Concrete 
Machinery Co. (Bournemouth) exhibited an hydraulic block-making machine. A 
new block-making machine, which is claimed to be one of the cheapest on the 
market and is built on sound and practical lines, was shown by Alessrs. H. and J. West 
&■ Co., Ltd. (72-4, Grays Inn Road, W.C.i). The " Bayliss " double-acting type 
block-making machine was shown by Messrs. W. Bayliss 6- Co., Ltd. (240-1, Dash- 
wood House, New Broad Street, E.C.2). A machine that will turn out lintels up to 
7 ft. long, or a number of smaller blocks at one operation by the insertion of liners, was 
shown by Messrs. R. H. Kirk &■ Co. (Newcastle-on-Tyne). In addition to the well- 
known " Ironite " brand of cement, Messrs. S. Thorneley Mott &- Vines, Ltd. (11, Old 
Queen Street, S.W.i) exhibited a useful concrete mixer (" The Wonder "), a dumping 
wagon, and " Aero " concrete blocks. Messrs. Henry Wilde, Ltd. (66, Victoria Street, 
S.W.) showed a wide range of power machines for making concrete blocks, especially 
noticeable being a power tamping machine which strikes a blow of 700 lb. at the rate 
of 70 a minute. 

The " Dussitorl " (Commander Thomas's patent), {zz-j and 228, Tower Buildings, 
Water Street, Liverpool) is a new machine, substantially made and easy to handle. 
In it,' there may be made at one time either twelve concrete bricks, two iS in. \ 9 in. 
blocks, or a sill, lintel, head, step, etc. It is a face down machine, so that a layer 
of rich facing concrete may be placed in the bottom and a leaner mixture or a mixture 
containing a porous aggregate tamped on top i)f it. As a semi-dry ct)ncrctc is used 



337 



BUILDING TRADES EXHIBITION, 192 1. OLYMPIA. [CQNCBETE] 

the blocks, etc., may be removed at once from the machine and, by a patent de- 
vice, immediately placed upon their ends to mature. This machine is being used on 
the Liverpool Housing Scheme. 



REINFORCEMENT. 

The uses of the " Keedon " and " Lattice " reinforcements were effectively displayed 
on the stand of Messrs. Johnsons' Reinforced Concrete Engineering Co., Ltd. (Lever 
Street, Manchester). The " Keedon " system, which is extensively used for reinforced 
concrete structures, is on the wedge principle, and combines the advantages of rigid 
yet adjustable members with a non-slipping bar ; the fact that the members are held 
in position with simple wedges permits of rapid erection to any design. The " Lattice " 
is in the form of rolls, suitable for floors, roads, etc. " Brictor " netting, for the 
strengthening of ordinary brick walls, was also shown, and its efficiency demonstrated 
by a section of 4I in. wall laid fiat across a 7-foot span. 

A new type of wire mesh 
reinforcement was exhibited 
by Messrs. Brown 6- Tawse, 
Ltd. (3, London Wall Build- 
ings, E.C.2). The mater- 
ial, which is designed for 
road foundations and other 
forms of concrete construc- 
tion, is manufactured from 
mild steel wire, cold twisted 
in order to eliminate the first 
stretch and thereby raise the 
tensional resistance of the 
metal. The twisted formation 
of the wire ensures a firm 
bond with the concrete. When 
used on large areas the net- 
work is joined together by 
pieces of the twisted wire sup- 
plied for the purpose, and 
there is no need to waste 
material by overlapping ; in 
fact, the wires used for joint- 
ing form part of the run of the material, and thereby effect a considerable economy. 
A further feature .of " B. & T." reinforcement is that there are no projecting -wires at 
the ends or sides, which sometimes lead to claims for compensation for torn hands on 
the part of the workmen. The wires are not specially fastened where they cross, but 
their spiral formation ensures secure locking when the network is stretched taut. 

In addition to their " Diamond Mesh " expanded metal reinforcement for roads, 
floors, etc., and " Exmet " reinforcement for brickwork, the Expanded Metal Co., Ltd. 
(York iNIansion, Petty France, S.W.i) exhibited a new type of reinforcement, called 
" Rotary Diamond Mesh " expanded steel. Like the " Diamond IMesh," this is also 
designed for road, floor, roof, or other slab reinforcement, and is supplied in rolls up 
to 60 ft. in length and 4 ft. i^ in. in width. 




B. & T." Reinforcement. 



CEMENT AND WATERPROOFING MATERIALS. 

The Cement Marketing Co., Ltd. (8, Lloyd's Avenue, E.C.3) showed a selection 
of samples of the cement products of the Associated Portland Cement INIanufacturers, 
Ltd., the British Portland Cement INIanufacturers, Ltd., Martin Earle & Co., Ltd., and 
the Wouldham Cement Co., Ltd., for which it is the selhng organisation. In addition 
to the samples of cement in various stages of manufacture, and cubes prepared for 
testing purposes, there was a complete set of testing apparatus used in connection wdth 
the requirements of the revised British Standard Specification, and practical tests 
were carried out on the stand. A hydraulic crushing machine, reading up to 50 tons, 

338 



[&^yj™J^j$^ BUILDING TRADES EXHIBITION, 1921, OLYMPIA. 

was shown in operation. Samples were also shown of lime, whiting, superfine Keene's 
and Parian cements and coloured concrete. 

The well-known cement waterproofing powder, " Pudlo," was exhibited by 
Messrs. Kerner-Greenwood & Co., Ltd. (King's Lynn), and models were shown to demon- 
strate its application, as follows :■ — (i) Apparatus for testing the resistance of cement 
to permeation by water under pressure ; (2) a section of concrete flooring with a 
waterproofed cement layer i in. thick on the upper surface ; the lower part of the 
slab, made of porous concrete, Avas immersed in water, while the top remained per- 
fectly dry ; (3) a length of drain-pipe jointed with cement and " Pudlo," which held 
water with no sign of leakage ; and (4) a tank built of thin porous blocks faced inside 
with waterproofed cement one-quarter inch thick, which also held water with no sign 
of dampness on the outside face. In addition to structures such as tanks, sewer 
tubes, artificial lakes, etc., wherein the concrete is continually covered with water, 
" Pudlo " is largely used for the cure of damp walls, flooded cellars, etc., and for the 
construction of dampcourses, and these applications of the material were also shown 
in a practical manner by models. A section of the stand which attracted consider- 
able interest was an exhibition of some of the original sketches by well-known artists of 
the artistic designs used by Messrs. Kerner-Greenwood in their advertisements in 
this and other journals. 

Messrs. Super Cement, Ltd. (10, Upper Woburn Place, W.C.i) demonstrated 
the water and oil-proof qualities of their specialities by practical exhibits, among the 
more interesting of which were some trays made of porous concrete which were ren- 
dered capable of holding water without the slightest trace of any leakage by brushing 
over the inside with a slurry of " Super Cement." The very high crushing strength 
of the material was shown by a specimen of ' ' Super-Cement " and sand under hydraulic 
pressure. 

The value of their products for improving concrete was demonstrated on the 
stand of the Torbay 6- Dart Paint Co., Ltd. (26-28, Billiter Street, E.C.3), including 
" Novoid," " Everok," and " Rencrete." " Nevoid " is apowder which hasachemical 
action on Portland cement and renders concrete water and oil proof by filling the 
voids with insoluble silicates ; " Everok " is a colourless solution that has a similar 
action on cement to the first-named, and is intended to prevent concrete floors from 
"dusting," as they are liable to do if not properly laid ; " Rencrete " is a similar 
solution, but specially prepared for water-proofing concrete, brick, plaster, etc. This 
solution is supplied in various colours, and can be used for the decoration of exist- 
ing work while at the same time rendering it weatherproof. The void-filling proper- 
ties of " Novoid " were demonstrated beyond dispute by samples of treated and un- 
treated concrete under microscopes, which gave visual evidence of the dift'erence 
claimed. 

On the stand of the Adamite Co., Ltd. (Regent House, Regent Street, W.i) was 
shown " Anti-Hydro " cement waterproofing material. This waterproofer has a base 
of calcium chloride, which is neutralised by carbon compounds introduced tlirough 
a special process. It is claimed to have no acid reaction, and not to have any 
electrolytic action on steel. " Atlas " white cement was also shown on this stand. 

GENERAL. 

The application of concrete to the drainage and sewage purification of a country 
house was admirably demonstrated by Messrs. Tuke 6- Bell, Ltd. (27, Lincoln's Inn 
Fields, W.C.2), in the form of a model of a complete installation for such a purpose. 
This system consists of a concrete liquefaction tank, made in sections so that it can 
readily be put together on the site with a concrete cover in two pieces. The humus 
settling cliamber is fitted with concrete baftie and weir plates. 

CONCRETE PRODUCTS. 

A large assortment of concrete products were exhibited by The Croft Granite, 
Brick, (S- Concrete Co., Ltd. (Croft, near Leicester), including dressings for window 
frames, tubes for drainage, kerbs, heads, sills, flags, bases for gas stoves and cookers, 
reinforced beams, higli-tcnsion switch cells for electrical equipments, etc. This 
stand was quite a revelation as to what can be achieved in concrete, and the firm 

F2 339 



BUILDING TRADES EXHIBITION, 1921, OLYMPIA. [CQSfCRErE 



is now turning out well-designed window-frames in concrete on mass production 
lines. Especially noticeable was a very fine series of garden ornaments, that would 
add to the beauty of any park or garden. The firm also exhibited a concrete mantel. 




The ••Nautilus" Concrlti; Mantel Register. 

An exhibit of special interest now that the cost of working-class houses is receiving 
so much attention was that of The Nautilus Company (60, Oxford Street, W.i), 
who demonstrated the saving that can be effected by the use of built-in gas fires 
and the elimination of chimney bredsts and large flues. The face of the fire is built 
flush with the surrounding wall, and an escape for the fumes is provided by a small 
flue formed of pre-cast hollow concrete blocks. A further interesting feature on 
this stand was a concrete mantel in which one of the gas fires was set. This innova- 
tion, well-proportioned and moulded and cast in one piece, makes a welcome change 
from the stereotyped metal or tile surround, and its relative cheapness combined 
with its good appearance should assure it of a big future not only in the housing 
schemes but also in large houses, offices, etc. 

A good display of reinforced concrete fencing posts and railings was shown by 
Alessrs. C. R. Building Constructions, Ltd. (19, Castle Street, Falcon Square, E.C.i). 
There is, of course, no comparison between the durability of concrete posts and that 
of wooden posts, and the periodical painting required by iron and wood posts is a 
further factor in favour of concrete, the cost of upkeep of which is nil. When it is 
stated that the prices per yard quoted for these concrete railings are less than for 
other types of railings, they cannot fail to commend themselves to estate managers, 
farmers, and others, to whom the maintenance of whatever method is adopted for 
enclosing land is no inconsiderable sum. Further, the posts and rails may be had 
from stock. The Company also supplies concrete gates, both of artistic designs 
suitable for park entrances or plain. 

A large assortment of concrete sewer tubes, up to 6 ft. internal diameter, radial 

340 



1 



CONSTRUCTIONAL,] 
EMGINEEKING 



g BUILDING TRADES EXHIBITION, 1921, OLYMPIA. 



tubes, bends, junctions, tapers, gulleys, manholes, etc., were shown by Messrs. Sharp, 
Jones & Co. (Bourne Valley Works, Parkstone, Dorset), and admirably demonstrated 
this branch of concrete work. These tubes are not reinforced. 

The " Hume " reinforced concrete tube was shown by the Stanton Ironworks 
Co., Ltd. (Stanton), in sizes up to 5 ft. diameter. 





i 
\ 


^SBI^^HIi^^^HH 



"C.R. " Reinforced Conxrete Railings at Entrance to Chateau in France. 
EDUCATIONAL. 

The stand of the Concrete Utilities Bureau, of 35, Great St. Helens, took the form 
of a bungalow carried out in Tudor style. As this organisation exists for propaganda 
purposes in the interests of concrete, the display was not spectacular, but a good 
deal of useful information could be obtained either from the representatives in attend- 
ance or from the range of pamphlets which are issued for free distribution. The 
latest of the series (No. 14) deals with the artistic possibilities of concrete, especially 
with a view to showing the variety of pleasing effects, both as to colour and texture 
which can be obtained by the simple method of scrubbing or tooling the concrete 
surface before it has become thoroughly hard. This is the first of the Bureau pamphlets 
to be illustrated with coloured plates. 

Other publications which could be obtained at the stand were the recently issued 
book entitled Concrete Roads, the volume Concrete Cottages, Small Garages and Farm 
Buildings, a new edition of which is now in the press, and the monthly journal Concrete 
and Constructional Engineering. 




341 



A CONCRETE ROAD FOR HEAVY TRAFFIC. 



ICDNCBETE] 



A CONCRETE ROAD CONSTRUCTED FOR 
HEAVY TRAFFIC. 

The road here illustrated was constructed by Messrs. G. & T. Earle, Ltd., at their 
Cement Works, Wilmington, Hull, for the heavy motor and rully traffic passing through 
their works. 

The method of construction was as follows : — 

The old road was taken up and all soft earth removed till a solid foundation was 
found. Then 12 to 1 8 in. of solid filling — chiefly old broken concrete — was put in, 
the voids being filled up with small material. On top of this filling concrete consisting 
of gravel, sand and cement in the proportions of 5 : 3 : i, 6 in. thick, was placed. 
This concrete was left rough in order that the wearing surface should key into it, and 
the wearing surface was placed on this before the final set had taken place. The 
wearing surface consisted of concrete made from Whinstone chippings and cement 
in the proportion of 5 to i. The Whinstone Chippings were half inch and under, and 
the dust was so proportioned that no sand was necessary. 

The surface was V'd as soon as the concrete had stiffened sufficiently to allow 
this ; this is seen in the illustration, a square steel bar with turned up ends being used 
for this purpose. 

All the concrete used on this work was hand mixed and hand rammed, the great- 
est care being taken in the grading and proportioning of the aggregate, and the smallest 
possible quantity of water was used. 

The greatest importance was also attached to obtaining a solid foundation, and 
to the quick handling of the concrete. 




Concrete Road at Wilmington Works Hui.r, with Concrete 
Silos and Concrete Chimney in background. 



342 



CEMENT NOTES. 



CEMENT NOTES. 

By Our Special Contributor, 



The Storage of Cement. 

It has been previously shown (see this 
Journal, Vol. XVI, p. 131) that when 
cement has to be stored for a period of 
months, or even years, preservation from 
deterioration is best secured by emptying 
the sacks and storing the cement loose 
in bulk when the formation of a thin 
crust on the surface prevents the absorp- 
tion of moisture by the cement as a whole. 
Prolonged storage is, however, rarely 
anticipated and consequently the empty- 
ing of the sacks is seldom done. The 
problem confronting the ordinary user 
is, therefore, how should cement in sacks 
be stored so that no deterioration will 
occur should it become necessary to keep 
it for two or three months ? 

The fundamental condition is, of course, 
that the storage building should be 
damp proof and weather proof, but this is 
really not enough, because the atmosphere 
always contains som.e moisture, no matter 
what the season or the temperature may 
be, and the affinity of cement for water is 
so strong that absorption of moisture, 
with consequent deterioration in quality, 
is bound to occur so long as the cement is 
in a changing atmosphere. It follows, 
then, that the more nearly airtight the 
building provided for cement storage can 
be kept, the less will be the effect on 
quality during storage. 

Where storage of a temporary character 
is required, as on a contract, wooden 
sheds can be made to serve the purpose. 
The floors should be raised above the 
ground and are preferably constructed 
with a double layer of boards with tarred 
paper between. The walls also may be 
made damp proof with one or more layers 
of tarred paper applied internally, while 
the roof should be externally protected 



with tarred felt. The doors should be 
tight fitting. 

Where the provision of a permanent 
cement store is needed, a concrete building 
should be considered, but the concrete 
must be dense in order to be waterproof, 
and such a building should be allowed to 
dry out thoroughly before it is used. 

Wlien storing cement in sacks, the 
latter should not be in contact with the 
walls of the building, but at the same time 
there should be as little free air space as 
possible. The sacks should also be kept 
from contact with a concrete floor by 
boards for battens until the concrete is 
several months old. 

If the sacks of cement are piled several 
tiers high, the pressure upon the lower 
sacks is sufiicient to consolidate the 
cement into fairly hard cakes, but this 
caking disappears on rolling the sack on 
the floor and should not be mistaken for 
air-setting due to absorption of mois- 
ture. 

When a cement becomes damaged by 
absorption of moisture, the result is seen 
in the formation of lumps and the cement 
is usually slow in setting and in hardening. 
In bad cases of damage, the cement never 
attains a satisfactory strength, but where 
the amount of moisture absorbed does not 
exceed 4 per cent., the hardening is merely 
retarded and the strength in two or three 
months is normal. A cement user or 
merchant who has the misfortune to 
possess cement damaged by storage 
should have the cement tested by an 
expert or by the manufacturer, either of 
whom will advise whether the lumps 
should be screened out and discarded, or 
whether an additional proportion of 
cement should be embodied in concrete 
to provide a normal strength. 



MEMORANDUM. 
Metal Forms and Economy in Paint.— In the construction of a large reinforced 
concrete building for the Columbia Gramophone Co., at Baltimore, steel forms were 
used throughout. The surfeices of the columns and ceilings were aftenvards painted, 
and owing to the smooth finish obtained by the use of the steel forms the amount 
of paint required was only half the quantity which it was originally estimated would 
be necessary. Steel forms are being extensively used in America for all descriptions 
of concrete work, with, it is stated, a considerable economy as compared with wooden 
form work. 

343 



NEW METHODS OF CONSTRUCTION. 



[QQNCRETEJ 







NEW METHODS 

OF 
CONSTRUCTION 



TT^-^^9^--...^ 




Tn recent issues we have given a list of new methods of construction which 
have been passed by the Ministry of Health in connection with housing schemes, and 
so that ovr readers may have fuller particulars of these methods, ue projiose putMsh- 
ing some further information regarding same, based mi details supjilied to us 
by the different firms putting forward new methods. — i:d. 



THE ANCHOR=TIE SYSTEM OF WALL CONSTRUCTION. 

This system, which may be adapted to either soHd or cavity wall construction, 
consists essentially of two leaves of pre-cast concrete 3-in. slabs, with a cavity between. 
This cavity may be filled with poured concrete, thus forming practically a monolithic 
wall, or a cored concrete tie may be laid which could be continuous throughout the 
wall and so form closed chambers in each course, or the ties may be arranged in series 
so as to form a continuous air space from damp course to roof. 

Before laying the tie, a strip of cement asbestos sheeting is placed across the 
cavity, and upon this the material for the tie rests. 

The two thicknesses of slabs are placed on the wall dry, one course at a time, 
each slab being separated from the one below by small pieces of concrete or other 
suitable material, so that a space is left which is eventually filled with the concrete 
poured from the inside which forms the joint. 

The dry built slabs are held in position by metal clips until the poured concrete 
has set. Although not required at every joint, the slabs being securely tied together 
by the poured concrete, metal ties are preferably used in the courses on which the 
roof and floor joints rest. 

By running a reinforced steel bar just over the cross ties longitudinally throughout 
the wall a great increase in strength is cheapty obtainable which might be of great 
advantage in mining districts where settlements are likely to occur. 

The following are the claims made by the inventor of this system, ]Mr. Thomson : — 

1. The novel form of building slab enables unskilled labour to bed and joint 
the slabs better with poured concrete than the skilled workman could with trowel and 
mortar. 

2. The poured concrete also carries the joists and so evenly distributes the floor, 
roof and other load stresses over both thicknesses of the wall that it thereby corre- 
spondingly increases the stability of the entire structure. 

3. Compared with an ii-in. hollow brick wall the S-in. cavity concrete wall 
has much greater lateral stability, and in semi-detached houses gives 6 per cent, 
more habitable space in each dwelling, and as this form of solid wall with 6 : i casing 
slabs and a continuous waterproofing core need only be 7 in. thick, it gives 8 per cent, 
more space in the habitable apartments than the brick-built dwelling. 

4. With the foregoing advantages in its favour concrete, wherever suitable 
aggregates are available, offers dry walled dwellings at considerably less cost than 
brick-built houses. 

The walls as shown meet the standardised requirements of the Ministry of 
Health. 

5. Another feature is that the cross ties are more than i| in. from the face of 
the wall. These ties automatically grip the sloping sides of the groove in the upper 
bed of the slab. 



344 



i 



(jONSTRUCTION A L 
F.Nr.lMEEi?lNG — . 



NEW METHODS OF CONSTRUCTION. 
^ATEMT aPPLlLD FOR 

3"0lab 4 2"C«viTY 4 3"jLAe> 




TmE POURLD CO/SCRELTE HFFICIE/STLV BETO AA^D JOl-STo TME PRE-CADT COMCRETE 

UMiT^ Rigidly T I Ei the: outer a/^d i^mer rnicKMESDEt) of 5lab5 togetmer 

TMEREBV GlVliSG WHAT ID IM EFFECT A nOMOLITHlG ^DTRUCTUPEl. CARRIE:^ THE. 
JOOTO. DiOTRIBUTEiJ THE.^TREi30EO,DUE TO ROOF A/ND FLOOR LOAO^, OVER 
60TM THlCK^tE>5:3L^ Or TME WALL A/SD T/-\UO CORReOPOMDIMGLY l^<CREAOCe> 
TME. ^TAdUTY OF TME BL)IL0I-MG 



^^^^.^ /J.^ ■' J ^ J ) J~n 





Air c!3Pace5l 
::)LAB 





Joi^T. : ! 

■ftlR DPA<t,EC) I 



:!)ECTiOMO OnOUlNG ARRAMGEHEMT OF 
UALL nE.3T:!3 FOR JOlOTl/^G 






m 










Pg 



^HCTIOM 
A-A 



l/SMEP. face: of :bLAe> 

FOR DOLID WALL 



:!)ECTlO(N 
B- B 



i)OLIO 

UALL 



TrtE PRE-CART 0/*iir^ ARt PLACED DRV OAlE COURRE i^T A 
Tint, A/^D. AFTER ADJUDTritMT AR TO LIAHE ArHD LEVEL . 
ARE LOCKED l/N POOITIO(S BY CO/N CRETE POURED l/*STO 
THE CAVITY BETUEETi THf^^LA&S TME PLAMR BELDU 
::)nOUJ THE UPPER BED OF QUOh-SD AMD OLABO. 



I Cav;ity I 



R05CRT TA\Onoon architect, Staple Mouoe, 52 Cha^^cery La/sE,L0MDOM.u.c2. 

Mb 



"ssaa 




CONCKETE^ 



J?rr 



■ 'i i 'iji r 

CONSTRVCnCfNA^ 

I ... ' ?.m 




B.S.P. CHATS 

ENTERPRISE 
the Soul 
of 
BUSINESS. 



Among all Engineers and Contractors who are in any 
way associated with Pile Driving operations, the name of 
THE BRITISH STEEL PILING COMPANY stands pre- 
eminent for their enterprising methods of doing business. 

As Pioneers in this country in the use of Steel Sheet Piling 
instead of Timber piles, Enterprise and Determination to be 
satisfied only with the best that money can buy or brains 
devise, have in a comparatively short time completely 
revolutionized this branch of Engineering. 

The Spirit of Enterprise shows itself in many directions. 
To mention one, and by no means the least — the readiness 
with which we take on our own shoulders the solution of the 
technical difficulties underlying so many pile driving pro- 
positions, placing the whole of our accumulated knowledge 
and experience at our Clients' disposal. 

In Pile Driving and Withdrawing Plant we stand unrivalled, 
our name upon it guarantees it to be the most scientific and 
up-to-date plant obtainable. 

We receive many expressions of approval from every part 
of the world, both as to our methods, 9ur manufactures and 
our publications. The latest is from a well-known Public 
Authority Engineer in Australia, who writes under date 
March 16th, 1921 :— 

" Your splendid little ' B.S.P.' Pocket Book has just 
reached me. Please accept my best thanks for same. I 
cannot but admire the enterprise that prompts a business 
house to advertise in this way." 



Several Thousands of this Book have been distributed. 
HAVE YOU HAD ONE? IF NOT, WRITE TO 

THE BRITISH 5TEEL PILING CO., 

DOCK HOU5E, 

BILLITER 5TREET, LONDON, E.C. 3. 



I 



Please mention this Journal when writing. 



346 



E 



CONSTBUCTION. 
ENGTNEERING 



3 



QUESTIONS AND ANSWERS. 



QUESTIONS AND ANSWERS 
RELATING TO CONCRETE. 

In response to a very general request we are re-starting our Questions and 
Answers page. Readers are cordially invited to send in any questions. These 
questions will be replied to by an expert, and, as far as possible, they will be 
answered at once direct and subsequently published in this column for the infor- 
mation of our readers, where . they are of sufficient general interest. Readers 
should supply full name and address, but only initials will be published. Stamped 
envelopes shmild be sent for replies. — En. 



Question. — V. W. writes : — In the case 
of a T-beam, continuous over a number of 
supports, when, as is usual, the beam has to 
be increased in depth at the supports to get 
sufficient area of concrete in compression 
to safely resist the max. negative B.M. there, 
in practice would the effective depth " d " 
be taken as " a " or " b," see sketch ? 

Answer. — Whether the depth should be 
the full depth [a) in sketch, or the depth 
(6) at the bottom of the haunch where it 
joins the large column, depends entirely 
on what moment has been taken. If the 
moment allowed for has been Ma, that is 



the maximum reverse moment which can 
occur on the centre line of the support, 
then it would be quite justifiable to cal- 
culate for the full depth {a) as shown on 
the sketch. Conversely, if the bending 
moment at the support has been reduced 
to allow for the width of support and is 
taken equal to Mb as in the moment 
diagram which has been added to the 
sketch in question, then the depth should 
be taken as equal to (6) in the sketch. 
As a rule, in practice the same result is 
obtained whichever of these two methods 
of calculation is adopted. 




j((„>t^2a|U^ 




{Continued from page 320.) 

ample resistance can be provided. The foundation on the lower side must be built 
at a suitable depth and subjected to a light load. The foundation on this upper or 
valley side should be built in such a manner as to be dependent on the size of the base. 

Tlie value of this method of construction lies in the enormous resistance to pres- 
sure of the main wall and to the very small changes in volume of the reinforced con- 
crete. Moreover, if through any carelessness in construction any part should give 
way repairs are much easier than in solid masonry or mass concrete. 

The construction is such that all leakage is confined to the permeability of the 
materials used and to errors in building. Any part of the structure may be readily 
examined. Turbine supply pipes may be mucli shorter than with mass construction. 
Tlie saving in cost depends on relative prices of tlic materials used for mass and rein- 
forced concrete, but as only 40 per cent, of the material required for mass concrete 
is I'cciuired, the saving is very considerable and probably averages 15 per cent, on 
tlic structure and about 50 per cent, on the cost of supply jiiping. 



347 




PCONCBETEX 



CONSTRUCTIONA 1^ 
EJSrGINE.E:RI'NG - 





Big Batches Delivered Quickly. 

WHEREVER Concrete is required it 
can be produced quickly and 
economically, in large, thoroughly 
mixed batches, if the " Victoria " Concrete 
Mixer is used. The model illustrated here 
— one of a series giving outputs varying 
between 54 and 3^ cubic feet per batch- 
is particularly suitable for road building. 
The long arm saves much time and labour 
in handhng, and possesses a delivery 
radius sufficient to meet all practical 
road building needs. For particulars of 
" Victoria " Concrete Mixers please con- 
sult Catalogue M.D. 103— free for the 
asking. 

STOIHBM^ITr 

(MIXER DEPARTMENT) 

11.VICTORIA ST.. LONDON S.Wl 




Please mention this Journal when writing. 



348 



\E 



CONSTRUCT]! 

ENGTNEEfilNG 



ICJMAq 



MEMORANDA. 



""iimiiilUJir" 

n 




MEMORANDA. 



Memoranda and Xews Hems are presented under this heading, with occasional 
editorial comment. Authentic news will be welcome. — Ed. 



ir^2l& 



CONCRETE HOUSING SCHEMES. 

Bexley. — The rapidity with which concrete houses can be erected is being demon- 
strated at Bexley, where houses have been built up to the roof level in nine days. 
The houses, which are being constructed on a concrete block system devised by the 
Clerk of the Works to the Urban District Council, were commenced on ]\Iarch 2, and 
on March 13 the roofs were slated. 

Glasgow. — It is reported that the Glasgow Corporation has invited a London 
firm of engineers to erect two experimental cottages on a special method of concrete 
construction, and that if the result is satisfactory as regards cost and speed of erection, 
the whole of the Corporation's housing schemes, estimated to cost ;^3, 500,000, will be 
carried out on this system. 

Glasgow. — In giving evidence before the Government Committee that is inquiring 
into the causes of the high cost of building in Scotland last month, Mr. Peter Fyfe, 
Housing Director of the Glasgow Corporation, submitted some information in regard 
to the use of concrete blocks for housing schemes. He stated that the Chief Surveyor 
to the Glasgow Housing Department estimated that a very substantial saving could be 
effected on the various types of houses by the use of concrete blocks amounting to 
;^49 135. 4^. for three-apartment flats, and £45 175. 11 d. for four-apartment flats per 
house. There was also a big saving in time and skilled labour ; only one-fourth of the 
skilled labour necessary for construction in brick was required for concrete block houses. 

Ripon. — An interesting scheme is on foot at Ripon, where the Town Council has 
asked the ^Ministry of Health for permission to take over the concrete buildings erected 
for the Army at Bishopton for the purpose of converting them into working-class 
dwellings, to form part of the Council's housing scheme. 

Sheffield. — As an objection on the part of the Housing Commissioner to the tenders 
for the concrete houses on the Mears Estate of the Sheffield Corporation, these tenders 
have now been reduced from ;/,3i 1,378 to /297,6io, and have been accepted and 
amended. 

PROSPECTIVE NEW CONCRETE WORK. 

Burnley. — Waterworks. — The Burnley Corporation lias received the sanction of the ^linistry of 
Health to a loan of £50,000 for extensions at the waterworks. 

Darli.vgton. — Waterworks. — The Darlington Corporation is considering an expenditure of 
£114,000 on waterworks extensions. 

Darlington. — Waterworks. — The Darlington Corporation has decided to apply to the Ministry 
of Health for sanction to a loan of £114,000 for extensions and improvements at the waterworks. 

Dartford. — Wharf. — The West Kent Main Sewerage Board has received the sanction of the 
Ministry of Health to a loan of £212,663 for the extension of its wharf at Dartford, including £103,816 
for reinforced concrete work. 

Harti.kpooi.. — Sea Defence. — A Ministry of Health inquiry has been held inta the application 
of the Hartlepool Corporation for sanction to borrow £16,500 for sea defence works. 

I,i;rni. — Docks. — The Leith Dock Commissioners have prepared a scheme for the extension of 
the Docks at tliat town, at an estimated cost of £300,000. 

Nr:w Zkaland. — Harbour Works. — The Tauranga (New Zealand) Harbour Boatd has received 
an Order in Council authorising the expenditure of £125,000 for the improvement and development 
of the harbour. 



349 



MEMORANDA. [CQNCKCTE] 

Penkitii. — Bridal'. — The rciuitli Kunil District Council is considering a proposal fur Hk- erection 
of a bridge over the river Wath, at Ivesgill. 

Preston. — Wutcnvorks. — The I'rrston Kiiral District Council has received sanction to a loan of 
£13,830 for a water supply scheme at I'arington. 

Kknikiav. — Dock'i. — Tlie Trustees of tlie Clyde Navigation Trust have decided to proceed with an 
extensive scheme for the improvement of the docks at Renfrew, involving an expenditure of about 
£280,000. 

Vancouver. — Harbour Works. — ^The Vancouver Harbour Commissioners are considering a scheme 
for the construction of a dam, locks, etc., at the harbour, at an estimated cost of three million dollars. 

TENDERS ACCEPTED, 

Belfast. — The Belfast Corporation lias accepted tiu- tender of Messrs. Concrete Piling, Ltd., for 
the construction of a new electricity generating station, at /,76,H33. 

BRADioRn. — Tlu' Bradford Town Council lias accepted tlie tender of the Expanded Metal Co., Ltd., 
for the reinforcement required in connection with the construction of concrete foundations at No. 4 
Boiler House at the Valley Road lilectricity Works. 

Brentford. — The Brentford Urban District Council has accepted the tender of Messrs. W. Ashby 
& Son, of Greenwich, for the supply ot 120 tons of cement, at £.\ lov. 6d. per ton. 

Harrogate. — The Harrogate Town Council has accepted the tender of Messrs. Hymas for the 
construction of a concrete floor at the electricity works, at £i,49(> 14s. 

Leeds. — The Leeds Corporation has accepted the tender of Messrs. T. Ward, Ltd., for the supply 
of a concrete mixer at £120, and a stone breaker at £108, and the tender of the Cement .Marketing Co., 
Ltd., for the supply of 230 tons of cement, at y8s. ^d. per ton, in connection with the construction of 
the Dewsbury Road Reservoir. 

Lewisiiam. — The Lewisham Borough Council has accepted the tender of Messrs. The British 
Reinforced Concrete Engineering Co., Ltd., for 2,700 superficial yards of road reinforcement fabric, at 
3s. id. per yard super. 

London (Battersea). — The Battersea Borough Council has been recommended to accept the 
following tenders : — For supply of concrete breaker, Messrs. Goodwin, Barsby & Co., Leicester, £227 ; 
for concrete mixer, Messrs. Millars' Timber & Trading Co., Ltd., London, £300 ; concrete kerbing, 
Empire Stone Co., Ltd., London, £167 7s. yd. 

MusKHAM. — Messrs. Walter Scott & Middleton, of London, have been awarded a contract for the 
construction of a reinforced concrete bridge over the Trent at Muskham, near Newark. The cost will 
be about £50,000. The total length of the bridge will be about 300 ft., and there will be two spans 
of over 100 ft. each, supported by a pier in the centre of the river. 

Plymouth. — The Plymouth Town Council has accepted the tender of Mr. W. J. Pearce for the 
erection of one pair of concrete houses on a special system of construction, at £815 12s. 6d. per house. 

Romford. — The Romford Urban District Council has accepted the tender of Messrs. R. G. Ward 
& Co. for the supply of concrete tubes at the sewage farm, at los. 6d. per foot run. 

Sheerness. — The Sheerness Urban District Council has accepted the tender of Messrs. T. W. 
Pedrette, of Bush Hill Park, Enfield, for the construction of about 2,640 lineal yards of egg-shaped 
concrete sewer tubes, from 2 ft. 9 in. by i ft. 10 in. to 9 in. diameter. 

Sheffield. — ^The Sheffield Corporation has accepted the tender of Messrs. Holloway Bros., of 
London, for the construction of foundations and concrete flooring at the Damflash reservoir, on a 
cost-plus basis not to exceed £1,000. 

Sheffield. — The Sheffield Corporation has accepted the tender of Messrs. Hadkin & Jones, Ltd., 
at £3.790 los., for the construction of the first portion of the reinforced concrete retaining wall and 
foundations in connection with the new Central Stores Depot. 

WicKLOw. — The W'icklow Foreshore Committee has accepted the tender of Mr. John Kane, of 
FitzwUliam Road, Wicklow, for the supply and laying of 80 large concrete blocks at the base of the 
pier. 

Yeovil. — The Yeovil Town CouncU has accepted the tender of Messrs. Johnson's Reinforced 
Concrete Engineering Co., Ltd., for the supply of steel reinforcement in connection with the proposed 
new reservoir at Henford Hill, at £1,148 14s. 

TENDERS INVITED. 

Mansfield. — May 12. The Mansfield Borough Council invites tenders for the erection of 300 
or a lesser number of houses. Plans, etc., from Mr. W. Thompson, Borough Engineer and Survej'or, 
Market Street, Mansfield. Deposit, £2. 

Sidmouth. — May 16. For the erection of 56 houses, for the Sidmouth Urban District Coimcil. 
Plans, etc., from Mr. R. W. Sampson, Architect, Manor Offices, Sidmouth. 

Menston (Yorks). — May 18. For the erection of houses, for the Wharfedale Rural District Coun- 
cil. Plan, etc., from Mr. O. Holmes, Architect, Boroughgate, Otley. 

Whitley 13ay. — May 19. Erection of new Post Office, for H.M. Commissioners of Works. Forms 
of tender, etc., from Contracts Branch, H.M. Office of Works, 63, Westgate Street, Newcastle-on-Tj-ne, 
or King Charles Street, Westminster, S.W.i. Deposit, £1 is. 

Bramall. — -May 24. For erection of 12 houses at Bramall, for the Hazel Grove & Bramall Urban 
District Council. Forms of tender, etc., from Messrs. Adshead & Topham, 23, King Street, Manchester. 
Deposit, £1 IS. 

BoMB.\Y. — May 31. Construction of about 105 miles of steel and reinforced concrete pipe lines 
for the Bombay Corporation. Specifications, etc., from Messrs. Taylor & Sons, Consulting Engineers, 
36, Victoria Street, Westminster, S.W. i. Deposit, £100. 

Pulborough. — June 30. The Pulborough Rural District Council invites tenders for the erection 
of 30 cottages. Plans, etc., from Mr. P. Ayling, Clerk to the Council, Storrington, Pulborough. 

350 



CONCRETE 

AND 

CONSTEUCriONAL ENGrNEEMNG 



Volume XVI. No. 6. London, Jpxe, 1921. 

EDITORIAL NOTES. 



A PLEA TO ARCHITECTS FOR COURAGE IN DESIGNING. 

A CORRESPONDENT Wilting in a contemporary over the signature " Provincial 
Architect," whilst admitting the impossibility of trying to ignore and ban re- 
inforced concrete, yet feels that its use, in the most efficient way, cannot but act 
to the eventual detriment of architecture. We feel that this fear is shared by 
many members of the architectural profession. The advent of a new means for 
the more efficient performance of an old function is always a matter of alarm to 
the majority. And as an analogy to this particular case the advent of the motor- 
car may be cited, when it was predicted that the charm of the horse equipage was 
to be supplanted by something hideous and quite incapable of achieving beauty. 
Yet now we see that a motor car has evolvedabeauty of its own, equalling, if not 
surpassing, its predecessors. Furthermore, the ugly and badly-designed motors 
were just those early ones that endeavoured to simulate the form of the carriage ; 
and it was only when they emerged from the tradition of the past (without alto- 
gether discarding that tradition) and evolved a form of their own, intrinsic with 
their manufacture and their purpose, that they became beautiful. 

Reinforced concrete will only remain architecturally unsatisfactory just so 
long as its designers remain too self-conscious, and endeavour to perpetuate in a 
new material forms whose suitability belongs to others. The full possibilities of 
reinforced concrete are as yet unknown and untried, and it must be allowed time 
to evolve its own forms which will arise from its particular needs and limitations, 
and from its employment in the most efficient manner. 

There are other aspects of the question. Architecture is subservient to the 
requirements of humanity, and a material the use of which has " brought light, 
airmess, cheerfulness, and comfort in working, into the lives of hundreds of 
thousands of people, whose lot it is to labour in those hives of industry " (factories) 
must be welcomed as an event of inestimable importance in the history of 
humanity. And a building that confers these great advantages cannot be devoid 
of the highest architectural merit beside which the shape of a moulding or the 
overhang of a cornice become matter of utter insignificance. No great architecture 
will ever be produced by talking about cornices and pilasters as if they are some- 
thmg extraneous to a building, to be added here, or omitted there, A cornice has 
a definite architectural function to perform ; that of protecting the top of a wall, 
and a pilaster emerges where additional strength is wanted. The requirements 
of reinforced concrete have as yet to evolve, and these will develop into sig- 
nificant features as surely as they have done so in the past with other materials. 
The factors that go to make aesthetic appreciation are many, but among 



351 



A PLEA TO ARCHITECTS. [CQNCTETEl 



the most important are historic association and famiUarity. The former is largely- 
responsible for the deplorable practice of selecting styles in which to design a 
building, and the latter so often compels the unnecessary addition of a cornice 
and a pilaster where neither is essential. These factors cannot, and should not, 
be ignored, but they must be made subservient to an infinitely greater and wider 
vision if a great and satisfying work is to be produced. 

" Provincial Architect " deals at some length with the fitness of reinforced 
concrete for building factories, going so far, it would seem, as to show that the 
ideal requirements of this class of building have never been adequately met 
until this material made its appearance. He admits that the new factory is fit, 
since light, air, and unobstructed floor space are obtained, but because, in hi.s 
opinion, the building is not also fine he seems to deplore the use of the material, 
while yet realising that it is the right material for the purpose, just as, to revert 
to our former analogy, others may, while admitting that the function of a vehicle 
is to transport persons or things from place to place with the utmost expedition 
compatible with safety, have feared and dreaded the use of the internal combustion 
engine as a driving power for locomotion. A little consideration will show that 
the objections of " Provincial Architect " are not radically architectural ; their 
origin is deeper. They refer to the requirements of a building which include the 
provision of large voids, of equall}' spaced floors carried upon equidistant supports, 
and the like, rather than to the building itself, and these requirements are the 
result of contemporary social organisation. The duty of the architect is not to 
dictate the purpose that his building shall serve, or the conditions under which 
he will attempt to provide such service, these things, to which he may or may not 
be sympathetic arise, from the industrial, sociological, and spiritual needs of the age. 

Will a brick or a stone factory be more beautiful than one built in reinforced 
concrete ? It will not, because neither of the former materials are so suited to 
factory requirements. Can a factory be beautiful ? This is another and irrele- 
vant question, which, interesting as it is, cannot be here dealt with, but it is the 
question indirectly raised by " Provincial Architect." Cannot a factory be 
beautiful unless it be made to look like a cathedral or a town hall ? Such a trend 
of thought leads nowhere — or everywhere ; absolute beauty in architecture cannot 
be considered apart from moral values. We may, and indeed should, obtain 
greater aesthetic satisfaction from the contemplation of a cathedral than a factory, 
because the former is expressive of finer aspirations than the latter, yet archi- 
tecturally both may near perfection. 

We admit that the problem confronting the architect who designs in reinforced 
concrete is a difficult one. The uses to which the material can be put are so 
diverse and its constructive limitations are so few. Limitations are necessary 
to the designer, and if they are not imposed from without they must be self- 
imposed. There will always be good buildings and bad buildings, whatever be 
the material or the building. But if the approach be pusillanimous the result 
will inevitably be worthless. The designer should be equipped with a sense of 
the past and of the great architectural traditions, both national and universal, 
and, of course, with a knowledge of the material with which he will build, but he 
must steadfastly refuse to think in terms of cornices and pilasters, for unless he 
does so he will never assist in the evolution of a great tradition for the new 
material which he is handling ; he will but deck it out in dead clothes. 

352 



e^ 



3^ 



i 



CCINSTBUCTJICSMA 
EJMGTNEERING 



^ 



A HOUSE AT CHE AM. 




A CONCRETE HOUSE 
AT CHEAM. 



We have on many occasions illustrated and described houses built in concrete 
which should sufficiently refute the fallacious opinion, still held in some quarters, 
that a concrete house of architectural merit and distinction is impossible ; the 



r^.,.n^.,^j.r^ HOVSE AT CHEAM SVR^R^E Yy^''^^^^M'!>•'C^r- 
| I 1 




s^ITTISE 



m I m 



r^ 




isyj®. 








Fig. I. Elevations and Plans. 

majority of the examples, however, except those of cottages, have come from 
America, where the prejudice against the material is almost non-existent ; it is, 
therefore, with particular pleasure that we show this month an all-concrete house 
which is of completely English origin. 

The house was begun soon after the Armistice, and it was the difficulty in 
obtaining bricks in adequate quantities, coupled with the building owner's desire 
to have the work completed as soon as possible, that prompted the use of con- 
crete. And, having decided to employ concrete as a substitute for brickwork, 
it was determined to construct the whole building in this material. The external 

353 



A HOUSE AT CHE AM. 



(CDNCRETEJ 



walls are constructed with blocks made on a Winget machine. A 2-in. cavity 
is formed and the inner leaf is made of aggregate of a more porous nature than 
the outer. The blocks are tied with wall tics in the usual way. 




Above the ground floor windows and at first floor level an unbroken cornice 
completely surrounds the house, above this springs the roof. This is the most 
interesting and enterprising feature of the design. In the first place it is a man- 
sard roof : a roof form the more general adoption of which we have often advo- 
cated. Its advantages are many, and the fact that English builders have 



354 



i 



7 CONSTRUCTIONAL 
ENGI7SEER1NG — ; 



A HOUSE AT CHE AM. 



continually eschewed it constitutes an insular peculiarity for which it is difficult 
to account. Secondly, it is a form particularly suited to concrete, which admits 
of a much lower pitch than other coverings ; indeed, in this house the central part 
of the roof is flat, with merely a slight fall to carry off the rain. The roof being 
a homogeneous mass is, in fact, a self-supporting inverted basin. It was cast 
in situ between shuttering and is of course reinforced throughout. The first 
floor ceiling is suspended from the roof, and the intervening space acts as an 
insulator and thus maintains an even temperature. The flat portion of the roof 
is asphalted, the pitched portions are covered with slates on battens fixed to the 
concrete. The first floor is constructed with slabs and beams, and some of the 
working details in connection with these are shown in Fig. 2. 




Fig. 3. A View of the Hall during Building OpERATio>rs. 

Turning now to the plan of the house, it will be seen that this presents many 
points of interest. The arrangement about two clearly defined axial lines is 
typical of planning which seeks to adjust itself to modern needs by a return to 
simpler and more dignified forms. It is, moreover, a form eminently suited to 
the method of construction. The shape of the hall, with its open oak staircase, 
the balance of the main rooms, and the grouping of the stacks along one of the 
axial lines are all points of interest. On the first floor the same balance is main- 
tained in the disposition of the five bedrooms and the two passages. Fig. 3 
gives a view of the hall, during building operations, in which the staircase well 
is seen and the arched openings leading to the lobby and to the verandah. 
Fig. 7 is a view from the front during erection ; concrete blocks can be seen in 
the foreground. 

The half-inch and full-size drawings show the care that has be^n bestowed 
upon all the details whose treatment has a traditional basis but yet is redolent 
of originality, as for example in the fluting on the chimney stacks and the archi- 
traves to the small windows that flank the front door. The grouping of the 

355 



A HOUSE AT CHEAM. 



!CDNCk>ii:rEJ 




356 



E 



CONSTBUCTIOTJ. 



(aD 



^ HOUSE AT CHE AM. 




357 



A HOUSE AT CHE AM. 



ICDNCROEJ 



dormer window into pairs produces a delightfully rl.ythmic effect which is best 



apprehended in the i^crspcc 



tive sketch. The flulint< molif is also used on the 




gate piers, carried out likewise in concrete. The outside surface of the walls and 
chimney stacks are cement rendered to a thickness of ^ m. 

358 



s 



CX?NSTRUCT1CSMAL 
ENGTNIXRING — ; 



A HOUSE AT CHE AM. 



A close study of this building will show that, although it entails the employ- 
ment of a comparatively new material, a material whose full potentialities are by 
no means realised, it is not necessary to sever connection with the past in order 
to produce a design which shall possess intimacy with the material. Indeed such 
a course would be an error. When designing in brick, or stone, or any age-long 
recognised material the weight of tradition is heavy. The past, with its associa- 
tions and experiences, makes itself felt by any one who has studied the art of 
architecture with assiduity, and who has in so doing related its products to the 
period of their production. The designer in concrete is certainly less hampered 
by such inarticulate influences, so that, while yet seeking guidance from the past, 
he feels himself free to adapt his design so as best to meet the requirements of a 
new material. His problem is to utilise this in a workmanlike and economical 
manner while still preserving a broad vernacular tradition, and remembering that 




lie. 7. A \'IE\V FRO.M THE FRONT DURING ERECTION. 

an appreciation of form and indeed of beauty is to some extent dependent upon 
familiarity. Architecture is more communistic than the other arts, and the per- 
sonal aspect should never be allowed to obscure this more comprehensive outlook. 
Unrestrained personal desires and ambitions must end in architectural chaos and 
the consequent loss of national architecture. 

It is in domestic architecture that the vernacular traditions are most potent 
in England. The history of the nation can be less clearly discerned in its public 
buildings, and the great traditions of church building have long since been lost 
in the devious paths along which designers have wandered owing to the growth 
of their self-consciousness. With the advent of reinforced concrete as a material 
for house construction a new situation arises, for out of the old traditions a new 
one is to be built up to meet the particular requirements, and a great responsi- 
bility rests with those engaged on such pioneer work. The house at Cheam seems 
to meet the new situation in the happiest manner. With its roots in the past it 
yet thrusts forward new shoots full of promise for a virile future growth. More- 
over, it proves indisputably the suitability of concrete for this new purpose. 

The architects are Messrs. A. W. S. Cross, M.A., F.R.I.B.A., and Kenneth 
M. B. Cross, B.A. The consulting Engineer was Mr. H. Kcmpton Dyson. The 
builders were Messrs. W. H. Lascelles, of Croydon. 

c 359 




rCDNCKETEJ 



.^^ 






THE GENERAL THEORY ] 
OF MOVING LOADS. 

By V. A. BAILEY, M.A., Oxford. 



The usual treatment of moving loads as given by text-books is somewhat heavy, 
and the results for the different cases considered seem to have no relationship 
to each other. From the student's point of view this involves an extra strain 
on the memory, while, on general grounds, it is always desirable to co-ordinate 
as many things as possible and to include all special rules in one general state- 
ment or law. 

We will examine the general case of a moving load of any distribution cross- 
ing a one-span girder. Three rules will be deduced which enable us to determine 
the positions of the load which produce maxima and minima values of the Shear- 
ing Force and Bending Moment at any given section of the girder. These rules 
will be proved for a restricted case first, and then extended to the quite general 
case. This procedure is not really necessary, but makes the theory easier to 
follow. 

Let us then consider the case of a load of any distribution, but restricted to 
remaining entirely on the span. 

L Load shorter than the span. 




Let X be the given section for which it is required to find the maxima and 
minima values of the S.F. and B.M. as the load moves along the span from left 
to right. 

Let W =total load on the span. 
PFi=the load to the right of X. 
I =length of the span. 
The other quantities used are shown in the diagram. 

360 



[&^^gj.^^ THE GENERAL THEORY OF MOVING LOADS. 

As the load moves all the quantities will change, except /, x, z and W. 

Wy 
Nowi?2 = -7^, and hence if j'<.v {i.e., all the load to the left of X) then 

W 
Shearing Force F=R2 = --{y—z) and 

L 

Bending Moment M = ^{l^x) R.-, = ^^Btr^(j'^z) 

both of which increase in magnitude with v. 

We thus see that if the load is completely to the left, or completely to the 
right, then the S.F. and B.M. at ^ can be increased by moving the load uptoX. 

We thus obtain our First Ride : — 

X cannot lie outside the range of the load when maxima and minima values of 
F and M occur. 

We now require to find the positions of X within the load range which produce 
maxima and minima values of F and M. 

We have : — 



M = -^('-^'--^ 



] y^ / w{y — x—z)dz 



(I) 

(2) 



F is a max. or min. when ^- = 0, i.e., when 

ay 

W dy_ d 

T j7:~x. / wdz. 



f^ 



I dy dy 
=Rate of change with v of the hatched area in Fig. i. 

But y.=y— (a constant) from the figure 

dy W 

.' . -f-=i. Our condition then becomes ~-=^w^ 

dy I 

We thus have our Second Rule : — 

F is a max. or min. when the value of w at X equals the mean load per unit 
length of span. 

From (2) we get that M is a maximum or minimum when :— 
W{l—x) dy_ d /-w-* 

^ dy~d^J ^b'—x—z)dz 



From page 195 in the third edition of Todhunter's Integral Calculus we 
find that the R.H. side of this equation= /^Uz-\-o~o = ]]\ 

^ ■ , d y-v-x 

ur more simply ^y u'{y^x-^z)dz = Rsite of change with v, of the moment 



c 2 /- 

361 



V. A. BAILEY. [CDNCKErrEJ 

about A' of the hatched area, wliich latter is, without much difficulty, seen to 
be equal to Wj. 

Hence the condition is 

-1-=-, — = , giving our T/nrd Rule: — 

/ / — X X 

M is a max. or min. when the mean load per unit length of AX {or BX) equals 
the mean load per unit length of the whole span. 

We are now in a position to generalise the preceding results, to cover all 
cases of moving loads on a Single Span. 

Let the load be partly on and partly off the span as shown in Fig. 2. 



Fig. IL 




Let W be the total load on the span. 

The rest of the notation is the same as before. We must now regard z and 
W as not remaining constant w^hile the load moves. 
For a movement dy we have dW=^dy. 
Also, by moments about the right end of the load d{Wz) =y{^dy) 

dW ^ - d{\Vz) ^ 
Hence -^-=c and -^--=yG 
dy dy 

=W^y^-y^ 
=W 

[This result can also be obtained by considering the effect on i?., of moving 
the load a distance dy.] 

Differentiating equations (i) and (2) with respect to v will now give us exactly 
the same conditions for maxima and minima as before. Hence the three rules 
hold universally. 

Mr. A. M. Maddox has pointed out to the author that the third rule may 
be deduced from an identical Rule given in Morley's Theory of Structures but 
proved only for a series of concentrated loads. 

The general case may be regarded as an infinite series of concentrated loads, 
and thus the same rule is applicable to it. 

We will now examine some particular types of moving loads in the light of 
our Three Rules. 

L Single Concentrated Load. 

The appropriate graphic representation of such a load is a very tall isosceles 
triangle with an extremely narrow base. The common representations by means 
of circles plainly cannot be regarded as ze'-diagrams. 

The First Rule tells us straight away that the load must be over the given 
section in order to produce max. and min. values of F and M. 

362 



[&^.mSNG^ THE GENERAL THEORY OF MOVING LOADS. 

II. TiO'o Concentrated Loads. 



W2 



FiG.nr 



Wi 



A B 

^^^^ "^ 1 W^ 

I "^ ^1 

Let C be the section in AB for which -— ^ = — ^ . The Second Rule tells us 

AC LB 

that F is a max. or min. when — — -=u''^ at A'. Our mode of representation 

makes it clear that this occurs only when Tl'i and Tl'o are each over A'. 

The condition that M be a max. or mm. at A is that — ^ 'T^^'iF^ 

I AA An 

where W^ and W^ are the loads on .4 A" and XB respecti\'ely. 

' ' XB I CB 

Hence if A is to the right of C then XB<TB, i.e. TI'g<TT'o- Thus, for sections 
to the right of C, Wo must be over the section to give the maximum value of M 
there. For sections to the left of C, similarly Wi must be over the section. At 
C, either Wi or W, will do. 

III. Short Uniform Load. 

The appropriate graphical representation for a uniform load is a rectangle. 
It is convenient to think of the ends of this rectangle as very slightly- sloping 
out from top to bottom. 



A / ' ' B 

™ ^ j^ fe f^ 

W WiU 
We have W^aic'i. Max. and mm. F occurs when w^ = j-=-y~ 

i.e. when zt'^ lies somewhere between w^ and o. 

This plainly can only occur when the (sloping) ends are over the given 

section. 

W W 
Max. M occurs when -^ =" ^ 
AX BX 

CX DX 

^■^•."^^" AX^BX 

The case of a uniform load longer than the span is also easily treated on these 
lines. 

{The author proposes giving the graphical constructions based on these Rules 
in a second article. — Ed.) 

363 



CONCRETE BUILDINGS IN SOUTH AMERICA. 



[Cr3NCBETEJ 




TWO RECENT REINFORCED 
CONCRETE BUILDINGS 
IN SOUTH AMERICA. 



THE ANGLO SOUTH AMERICAN BANK LTD., VALPARAISO. 

The building at present occupied by the Valparaiso Branch of the Anglo-South- 
American Bank, Ltd., was recently erected, to replace an old building destroyed 
by fire. The new building has been leased to the Bank as temporary premises, 
during the reconstruction of the Bank's own property in the same street (Calle 
Prat) which is now in full swing, and will be one of the most modern and perfect 
buildings in South America. We shall have the pleasure of giving our readers 
interesting details of this scheme when farther advanced. 

The building is of considerable extent, running through from one street to 




Fig. I. Temporary Premises for the Anglo South American Bank, Ltd.. Valparaiso. 



364 



&CONSTBUCTIOTMA1J 



CONCRETE BUILDINGS IN SOUTH AMERICA. 



the other, occup3'ing an area of upwards of 4,000 ft. The main entrance is in the 
Calle Prat ; the frontage to the Calle Cochrane being a story lower. This base- 
ment floor contains the very supersafe strong-rooms built by the Bank, of extra 
heavy concrete, reinforced with a steel network of | in. bars. 

The building was designed and erected by Mr. Robert Parker, Architect of 
Valparaiso, for the owner, Mr. Juan Brown. The facade is finished with white 
cement, in imitation of white dressed stone. All woodwork is of " lingue " (a 
very popular native lumber resembling birch), French polished in natural colour. 

The building at present under consideration is constructed almost entirely of 
reinforced concrete, the floors being reinforced with B.R.C. fabric ; the roof, 
however, is timber framed. 

NEW PREMISES OF THE CHILE TELEPHONE COMPANY LTD., VALPARAISO. 

These premises have been erected to receive the modern automatic plant which 
has been recently introduced into the Company's local service, and occupy a site 
a few hundred yards from the original central offices, which suffered very con- 
siderably during the terrible earthquake of 1906. As the new site is situated 
within the principal danger zone of this catastrophe, it was recognised that the 
only safe building S5^stem was reinforced concrete. 

The work of designing and carrying out the erection of a suitable building 
was entrusted to the local architects and engineers of the firm of Frederick Sage $c 
Co. Ltd. (London and Valparaiso). 

As this neighbourhood was originally reclaimed from the sea and has been 
made up from time to time, a solid foundation was unobtainable. WTiile exca- 
vating for preliminary investigation, three distinct levels of street paving were 
brought to light, about a yard apart. With a view to obtaining a safe base, a rein- 
forced concrete raft foundation was constructed, upon a complete system of 
concrete piles. 




liUlLUI.NO Hm IHK ClilLt TtLLFHONt Co., LtU. FiRST I'LOOR. 






CONCRETE BUILDINGS IN SOUTH AMERICA. 



[QQNCRETEJ 



The building is of reinforced concrete throughout, all floors being reinforced 
with B.R.C. fabric, as also the foundation and roof. 




Fig. 4. SnuwixG Roof. 



The roof is practically flat, with the exception of a slight camber in the centre, 
and is covered with a bituminous composition and roofing felt. 

366 



E 



CDNSTBUCnONAL 
FJMr.rNF.F.piNr. — ^ 



CONCRETE BUILDINGS IN SOUTH AMERICA. 



Notwithstanding the incombustible nature of the building, special measures 
have been adopted for assuring the safety of the employes in case of fire, by 
the erection of an iron exterior-emergency-stairs. 

A reinforced concrete tunnel is constructed underneath the building to contain 
the cables for the new system of subterranean telephone lines. 

The interior of the building is simple in construction but effective and is 
ifinished off in soft agreeable tones. 

The exterior is finished in white cement, tooled when set, in imitation of 
dressed stone. 

This is one of the first buildings in this country constructed of purely rein- 
forced concrete, without the aid of steel joists or beams. 

We are indebted to Mr. George Mallet for our particulars and illustrations. 




Fig. 5. General View. Building ior the Chile Telepuonl; Co., Liu. 



367 



THE CONCRETE INSTITUTE. 



ICDNCBETEJ 




THE CONCRETE 
INSTITUTE. 

MONTHLY NOTES. 

By the SECRETARY 



RECENT ELECTIONS INTO THE INSTITUTE. 



Members 



BuTTERFiELD, Ernest. 

Clarke, Ernest Mortimer. 

Hanauer, Herbert William. 

Newborn, Charles Reginald. 

Payne, Crompton Spencer. 

Smith, George Willie. 

Smith, William Herbert. 

Tomes, Francis W^illiam. 

Yearsley, Herbert Aloysius. 
Associate : — Jackson, Charles Albert. 

Associate-Members : — Borer, Oscar. 

Phillips, Edward Hyde Benjamin. 

Rogers, Albert William (from Student). 

Stevens, Donald Arthur (from Student). 

Tate, Newman. 

CONCRETE AGGREGATES (Continued). 

(39) Gloucester : — 

General description : Clean sharp sand and gravel. 

Source and locality of same : Gravel pits, Barnwood (2 miles from Glou- 
cester). 

How obtained : Open digging. 

From whom obtained : Messrs. Chambers and Company. 

Is available quantity limited ? Unlimited. 

Present maximum output per day : 200 tons (could be increased). 

Transport facilities : Road. 

Is there any provision at or near source for washing or crushing? 
W^ashing unnecessary — no crusher. 

Price per cub. yd., and where delivered : ys., delivered Gloucester, 

Kind of stone or coarse material : Limestone gravel. 

Kind of sand or fine material : Limestone gravel. 

Relative proportions of coarse and fine materials : Half and half. 

Shape of particles : Angular. 

Approximate percentage needing crushing to pass f in. screen : 10 per cent. 

Impurities present : None. 

General remarks : Good for concrete. 
The Manager of the Tytherington Stone Company at Falfield, Gloucester- 
shire, writes that their quarries, situated on the Midland Railway, furnish 



(39«) 



368 



I&g^iSI^J.^ ™J^ coxcrete institute. 

unlimited supplies of broken stone and chippings, suitable for concrete ; 
there are no facilities for washing the material. Some thousands of 
tons of material for concrete were supplied to the National Shipyards, 
Chepstow. 

(40) Gorleston : — Beach shingle and sand, containing 10 per cent, mud ; needs 

washing. (R.C.B.)* 

(41) Halifax : — There is some excellent stone. On the other hand, there is some 

soft sandstone, which is too weak for concrete. (R.C.B.) 

(42) Harlow : —Coarse sand (with 12 per cent, loam) and fine sand (with 4 per 

cent, loam), both kinds containing chalk. (R.C.B.) 

(43) Herefordshire : — 

General description : Gravel pit. 

Source and locality of same : Stoke Prior. 

How obtained : Raised by hand. 

From whom obtained : J. H. Davis, Leominster. 

7s available quantity limited? Xo. 

Present maximum output per day : None [sic). 

Transport facilities : Horse-drawn vehicles only. 

Is there any provision at or near source for washing or crushing ? No. 

Price per cub. yd., and where delivered: 3s., on site. 

Is composition uniform .^ Yes. 

Kind of stone or coarse material : Red sandstone. 

Kind of sand or fine material : Sharp. 

Relative proportions of coarse and fine material: 3 rough to i fine. 

Shape of particles : Rounded. 

Size of particles : \ in. to 3 in. 

Approximate percentage needing crushing to pass | in. screen : 50 per cent. 

Impurities present : Small amount of clay. 

Source of information : Mr. V. Godfrey, of Stoke Prior, the proprietor. 

Weight per cub. ft. dry : About i ton. 

* See previous issues for index letters. 



SOME METHODS OF SECURING IMPERMEABILITY^ 

IN CONCRETE. 

By EWART S. ANDREWS, B.Sc. (Eng.). 

The folloivino i-f an abstract from a Paper read at the One Hundred and First 
Ordinary General Meeting of the Concrete Institute. Mr. E. Fiander Eichdls, 
President, va.<i in the Chair. 

In many of the uses to which concrete is put, it is either of primary or secondary 
importance that the concrete shall be impermeable to the passage of water and other 
fluids. In many other cases, such as marine structures, it may be regarded as of 
secondary importance, because deleterious results are caused by the chemical and 
pliysical action of liquids which find their way into the structure of the concrete. 

In cither case it is verv desirable to avoid permeability. 

Causes of Permeability Troubles.— These come under three main headings :— 

(a) Caused by materials percolating through voids in the material. 

(b) Caused by the existence of cracks right through the concrete. 

(c) Caused by chemical action of materials upon the concrete even when 

there are no voids or cracks. 
Secondary actions often give rise to trouble under («) and (b), due to chemical 
or pliysical action of liquids which find their way into the pores of the concrete. 

Common Methods of avoiding Permeability.— These we may classify as follows, 
leaving out of consideration for llie present tlie question of cracks in the concrete : — 

369 



EWART S. ANDREWS. ICONCDFTF} 



(A) Void-filling methods. 

(i) Preventing voids by dense concrete. 
(2) Integral preparations. 

(a) Materials added in making concrete. 

{b) IVlodified cements. 

(B) Coating methods. 

(A). Preventing Voids by Dense Concrete. — There is no doubt that one of the 
best ways to make concrete impermeable is to grade and mix it properly. Careful 
experiments have shown that concrete can be made waterproof without the addition 
of water-proofing compounds. This applies particularly to the case in which, as in 
reinforced concrete, for purposes of strength it is desirable to employ a concrete com- 
paratively rich in cement. 

Instead of employing comparatively expensive materials to fill up the lioles in 
the concrete we should endeavour to prevent the production of such holes. 

If the concrete is too dry there will not be sufiicient water to ensure the complete 
hydration of the cement and air is likely to be retained between the particles, resulting 
in a spongy concrete ; if it be too wet then the excess water will ultimately dry out 
and will leave voids. 

Studies of Concrete by aid of the Microscope. — \'ery interesting and valuable 
data upon the consistency of concrete have been obtained by the use of the microscope 
by Mr. Nathan C. Johnson, who has expressed his views clearly if strongly in papers 
which will be found in Concrete and Constnictioiial Engineering, June-December, 

1915- 

Mr. Johnson pays considerable attention to the unhydrated cement to be detected 
in micro-photographs of concrete, and this question of unhydrated cement is of great 
importance in the problem of permeability which we are now considering. Briefly, 
he states that not more than 20 per cent, of the cement in concrete is hydrated and 
that the remaining cement merely acts as an inert space-filler ; he attributes this 
small amount of hydration to the high surface tension of the water and suggests that 
small quantities of substances such as alcohol, ether, sodium oleate, sodium hydroxide, 
etc., reduce the surface tension -of the water and increase the hydration of the cement, 
thus increasing the strength and impermeability of the concrete. 

" Integral " Preparations for preventing Permeability. («) Materials added in 
mixing the Concrete. — The method of reducing permeability of concrete by means of 
the " integral " system consists in the use of certain materials which are added to 
the concrete when it is being mixed ; the action of some of these materials may be 
described as inert, their function being merely to fill up the voids in the concrete. 
Others, commonly of the soap family, have a chemical action upon the cement ; while 
others are claimed to have a kind of catalytic action in promoting the formation of 
colloids which increase the hydration of the cement. 

Hydrated Lime. — Hydrated lime is a finely divided white powder made from 
ordinary lime by the addition of just sufficient water to ensure complete slaking, so 
that the heat generated evaporates all the excess water and leaves the product dry. 

Experience has shown us that the addition of hydrated lime causes the resulting 
concrete to be more dense and uniform ; the amounts recommended as the result of 
experiments by Mr. Sandford Thompson * are as follows : — 

Portland Hydrated Lime 

Cement. Sand. Stone. (% weight of cement) 

124 8 

I 25 4-5 12 

135 16 

In the report of the United States Bureau of Standards, it is stated that the value 
of hydrated lime as a waterproofing medium is due to its void-filling properties only 
and that similar results could be expected from any other finely ground inert material ; 
but the author believes that the effect of the lime in providing what practical men 
would call a " fatter " mixture is one of considerable value which most other inert 
materials would not possess. 

* American Society of Testing Materials, 1908. 
370 



[&c qs3TBucnCTs^ SOME METHODS OF SECURING IMPERMEABILITY. 

Other Inert Fillers. — A very large number of finely ground inert materials have 
been found to decrease the permeability of concrete ; mention may be made of felspar, 
clay, sand and Portland cement (ground finer than normal). Some authorities have 
held that clay has the effect of increasing the much-disputed colloid action in the cement. 

In considering the use of these inert fillers we ought always to consider whether 
we should not obtain as good results by the use of a correspondingly increased quantity 
of cement. 

Soap Compounds. — One of the oldest methods of waterproofing concrete was the 
Sylvester process which consists in applying coats of soap and alum. 

Other chemically similar methods consist in the addition of materials which will 
cause the formation of the insoluble calcium stearate in the pores of the concrete. 
Some of the best known preparations on the market are of this kind ; they often 
consist of powders made from lime, fat and an alkaline carbonate. 

There appears to be evidence that the void-filling materials of the soap type are 
liable to become ineffective in the course of time, due to the presence of various im- 
purities in the water or to the nature of the other fluid retained in the vessel which 
slowly dissolves out the aluminium or calcium stearate, thus leaving the concrete 
probably more porous than it would have been had the material not been added. 

Metallic Powders. — Many Avaterproofing and concrete-hardening preparations 
have been employed consisting of powdered pig iron or iron filmgs which oxidize and 
expand, thus filling the voids in the concrete. Small quantities of sal-ammoniac or 
flowers of sulphur are often added to assist in the oxidation of the iron. 

Silicates. — Sodium silicates (water glass) and potassium silicate, both of which 
are soluble in water, have been employed for increasing the impermeability of concrete. 
The function of these silicates is to form with the lime of the cement a calcium silicate ; 
but some chemists state that the amount of lime in the cement is insufficient for such 
action. 

{b) Special Cements. — A number of proprietary brands of cement have appeared 
from time to time in which various materials have been mixed with Portland cement 
clinker and ground up with it with the intention of increasing the impermeability of 
the cement. 

The cement of this type which is probably the best known to British engineers 
is that made in accordance with British Patent Specification No. 13542/14 (Goddard) ; 
in this cement the gypsvim is treated with a small quantity of tannic acid. 

From the tests of this material the author has seen and from the results of other 
tests substantiated by independent testing engineers, he is satisfied that this cement 
has less permeability than the standard cement. In one test which the author wit- 
nessed, a thickness of I in. of a concrete made of i part of the cement and 5 parts of 
crushed limestone successfully resisted a water pressure of 200 lb. per sq. inch. 

(B) . Coating Methods of securing Impermeability. — Many of the materials already 
referred to under integral compounds form the basis of methods of coating concrete 
with a view to preventing access of fluids into the structure of the concrete. In dealing 
with these coating methods we can consider two types of coating materials — (a) those 
employed to prevent the materials used from attacking the concrete chemicall3% and 
(6) those employed to form a dense impervious layer to the concrete. The aim with 
the second class will be to penetrate into the surface of the concrete and with the first 
to form a resistant skin outside the concrete. 

Sylvester Process. — Tliis is the equivalent of the soap and alum process previously 
referred to. 

Good results have been obtained with a solution of 2 ounces of alum per gallon 
of hot water and a solution of 12 ounces of Castile soap per gallon of hot water. The 
alum solution is applied first and worked in with a stiff brush and is immediately 
followed by the hot soap solution. The temperature of each Avash should be kept at 
above 100° I'. 

Paraffin (Wax) Process. — Many cases are recorded of successful coating to avoid 
permeability diKicultics by means of the paraffin process. Tlie paraflin may be 
dissolved in a high volatile compound to enable cold application ; the liquid is rubbed 
thoroughly into tlic surface with a stiff brush, three coatings being desirable when 
the surface is rough. A solution of one part paraffin wax with two parts kerosene 

371 



EWARf S. ANDREWS. [CQNCBETE] 

(paraffin oil) may be used. Some authorities recommend driving the material into 
the concrete by means of a blow lamp. 

Bituminous Compounds. — This class includes a large number of coating materials 
such as asphalt. Such methods of coating are comparatively expensive in practice 
and the materials require care in their selection to ensure that the coating shall retain 
the elasticity which is essential for the proper functioning of the material and yet 
shall not " run " at high temperatures. The liability of the coating to come away 
from the concrete also has to be considered. 

Special Chemical " Paints." — -A number of special chemical covering materials or 
paints have been devised with a view to resisting the action of special liquids under 
various temperature conditions. 

A coating preparation devised to provide an oilproofing material for tanks is 
patented in British specification No. 149365 (Ivinson and Roberts) ; it comprises 
30-65 parts by weight of chloride of zinc, 30-55 parts of oxide of zinc, and 2-20 parts 
of chloride of ammonia. 

Tests have been made by the National Physical Laboratory upon model reinforced 
concrete tanks coated in accordance with this process. The thickness of concrete 
was 3 in. and the internal dimensions gave a cube of 6 in. side. ' Tests were made up 
to pressures of 50 lb. per square inch with petrol, with petrol and paraffin in equal 
proportions, linseed oil and turpentine in equal proportions, and with water. In 
no case was there evidence of permeability. 

Contraction Joints. — The cause of leakage in concrete structures may be due to 
the development of actual cracks in the concrete and no amount of doctoring the 
concrete can remedy the trouble caused by cracks. 

Although it is true that many such cracks can be attributed to failure on the part 
of the designer to provide adequate reinforcement to carry tensile stresses, the principal 
cause of this difficulty is the contraction of the concrete in setting. On large structures 
it appears to be practically impossible to avoid such cracks, and the wisest plan is 
to induce them at specified places by the adoption of contraction joints — often referred 
to as expansion joints. 

American Bureau oJ Standards Investigation. — The subject of permeability of 
concrete has been experimentally investigated at length by the United States Bureau 
of Standards and a full report will be found in Technologic Paper No. 3, by Messrs. 
R. J. Wig and P. H. Bates. In these experiments a number of proprietary prepara- 
tions were taken and test specimens were tested ; the summary of the report appears 
to the author to be so important that he has reproduced it in extenso as follows : — 

" Portland cement mortar and concrete can be made practically w^atertight or 
impermeable as defined below to any hydrostatic head, up to 40 feet without the use 
of any of the so-called ' integral ' waterproofing materials, but in order to obtain such 
impermeable mortar or concrete considerable care should be exercised in selecting 
good materials as aggregate, and proportioning them in such a manner as to obtain 
the dense mixture. The consistency of the mixture should be wet enough so that it 
can be puddled, the particles flowing into position without tamping. The mixture 
should be well spaded against the forms when placed, so as to avoid the formation 
of pockets on the surface. 

"The addition of so-called ' integral ' waterproofing compounds will not com- 
pensate for lean mixtures nor for poor materials, nor for poor workmanship in the 
fabrication of the concrete. Since in practice the inert integral compounds (acting 
simply as void-filling material) are added in such small quantities, they have very little or 
no effect on the permeability of the concrete. If the same care be taken in making the 
concrete impermeable without the addition of waterproofing materials as is ordinarily 
taken when waterproofing materials are added, an impermeable concrete can be obtained. 

" The terms ' permeability,' ' absorption ' and ' damp-proof ' should not be con- 
fused. A mortar or concrete is impermeable (though necessarily damp-proof) as 
defined and used throughout this report, when it does not permit the passage or flow 
of water through its pores or voids. 

" The absorption of a mortar or concrete is the property of drawing in or engrossing 
water into its pores or voids by capillary action or otherwise. If the pores or voids 
between the grains or particles in the individual grains are sufficiently large and 

372 



l&^^TR^j^^ SOME METHODS OF SECURING IMPERMEABILITY. 

connected from surface to surface of the wall, the concrete will be permeable to water. 
If the pores or voids are very minute, but connect one with another, theoretically, 
they may act as capillary tubes, absorbing or drawing in and filling themselves with 
water ; but capillary forces will tend to hold the water in the pores and will prevent 
the passage or flow of water even though one surface of the wall may be exposed to 
considerable hydrostatic pressure. For all practical purposes a wall under such 
conditions would be considered perfectly watertight and impermeable, although it 
may be highly absorptive. If these minute pores do act as capillary tubes and are 
never minute enough to prevent capillary action, the moisture either as water or water 
vapour would in time penetrate entirely through and fill a concrete wall, no matter 
what the thickness or composition. In such a case the capillary forces would not 
permit an actual flow of water, but these forces may carry moisture, entirely filling 
the wall and, unless evaporation is retarded, the opposite face of the wall would appear 
■dry. In such a case the concrete would be considered impermeable but not damp-proof. 

"The damp-proofing tests as conducted would indicate that Portland cement 
mortars can be made not only impermeable but damp-proof as well, as defined above, 
without the use of any damp-proofing compound. However, these tests should be 
interpreted with caution as the evaporation may have been sufficient to care for the 
slight amount of moisture coming through the test pieces without indicating on the 
filter paper. Thus it cannot be stated that if a material were used which was damp- 
proof according to this test if used as a basement wall, one surface being constantly 
■exposed to moisture and the other surface in an inclosed room where there would be 
little or no circulation of air, that the interior surface would not appear damp and the 
atmosphere become saturated with moisture. The tests of coating materials as damp- 
proofing mediums can be considered as only preliminary, but the results, considered 
along with the chemical discussion, throw some light on their comparative merits. 
The mortar used in these tests was perhaps too coarse and too absorptive for a fair 
test, the purpose of the rough surface was to test the flowing qualities of the coating 
and it would seem that many of the failures may be due to the poor or imperfect 
spreading and adhesive quality. Several of the compounds deteriorated and proved 
their unfitness for the purpose intended. 

"Well-graded sands containing considerable graded fine material are preferable 
for making impermeable concrete, but if such is not to be had, fine material in the 
form of hydrated lime, finely ground clay, or an additional quantity of cement will 
be found of value. 

' ' Where Portland cement mortar is used as a plaster coat, if sufficient cement be 
used and the sand contains sufficient fine material (or fine material be added) and the 
mortar be placed without joints and well trowelled (care being taken not to over- 
trowel, which may cause crazing), the coating will be effective as an impermeable 
medium without the use of any waterproofing compound. 

"As a precaution under certain conditions, it is undoubtedly desirable to use 
bituminous or similar coatings, even on new work, as protection where cracks may 
occur, due to settling of foundation or expansion and contraction caused by tempera- 
ture changes. In large or exposed work it is practically impossible to prevent cracks, 
but where cracks can be prevented no coating whatever is required to make the 
structure impermeable. 

"The permeability of Portland cement mortars and concretes rapidly decreases 
with age. 

"None of the integral compounds tested reduced the absorption of the mortars 
before they were dried by heating at 212° F. Thus they would have little or no 
practical value. But some of the so-called integral waterproofing compounds did 
decrease the absorption obtained after drying the mortars at 212° F., and the rate of 
absorption was mucli slower in these cases. The addition of hydrated lime and clays 
seemed to have little or no eftect on the absorption. 

"The addition of any of the compounds tested to a mortar in the quantities used 
in tliese tests does not seriously affect the compressive or tensile strength. The addi- 
tion of the inert void fillers to mortars, as used in these tests up to 20 per cent, of the 
vohmie of cement, increases the compressive strength." 

Some Conclusions and Suggestions. — One of the difticultics incoming to practical 

373 



EWART S. ANDREWS. ' [(CTCBETEI 



conclusions on this subject is that so many of the data are based upon tests made under 
laboratory conditions and we have to decide as to how far we are to be guided in practice 
by the results of these tests. 

The trend of the evidence appears to be that if great care is taken in the grading, 
mixing and placing of the concrete, a voidless concrete can be obtained and that such 
concrete is as good as, if not better than, that obtained with the special preparations. 
Some of the advocates of these special preparations argue in their persuasive literature 
that in practice it is impossible to exercise the great care necessary for this result 
and that therefore some special treatment is necessary. Such statements are often 
supported by experimental test results made by engineers of imimpeachable standing 
and showing that an increased strength results from the use of the particular material. 
But the argument against laboratory conditions is a boomerang which may come back 
on the thrower. The test results obtained with special preparations are also made 
under laboratory conditions, and in the case of integral mixtures it may be assumed 
that the added materials will be more thoroughly mixed with the concrete than can 
be assumed to occur in practice ; if these materials are not uniformly mixed with the 
concrete in actual practice, as seems probable, it is at least doubtful if their effect will 
be as good as can be obtained in laboratory tests. 

Tensile Strain. — This question of colloid action is of importance in relation to 
impermeability if, as some people suggest, it would result in a more plastic material 
less liable to cracking, but it appears to the author that this question of yield or 
plasticity can be investigated as a fact apart from the theory of colloids. 

If the addition of certain materials to the concrete renders it more plastic, then a 
test specimen would show greater strain before fracture by tension than will occur 
without such material. The cause of cracking in concrete, which probably gives rise 
to much of the permeability troubles, is failure to contract without fracture. It is 
therefore suggested that the question should be tested by measuring the extension 
before fracture of tension specimens made from concrete treated by the various processes. 

Standard Penneability Tests. — It is well known that permeability tests upon con- 
crete made upon small specimens are likely to give more favourable results than one 
is likely to obtain with larger structures in practice and that microscopic cracks in the 
specimen may prevent percolation by water, whereas water would find its way through 
the correspondingly larger cracks in larger models. The author therefore suggests 
that in testing small specimens for permeability one sh